No first start?

mike_777 · 07-24-2002, 11:07 PM

Hey,

I was wondering if you guys could help me out. I have a 1990 lx 5.0. Sometimes I try to start the engine it wont fire. But when I do it a second time it does..... Do you folks happen to know why it is doing that? Thanks for all replies.

Philip

PKRWUD · 07-24-2002, 11:39 PM

You have a problem in your fuel system. The pressure doesn't build up fast enough (weak pump), or you have a leak some place that is preventing the pressure from remaining after the pump is turned off (leaky injectors, cracked hose near the pump inside the tank). You need a fuel pressure gauge to test the system, and to determine where the problem lies. Next time you try to start it, do this:
Turn the key ON, but do not try to start it. Wait 2 seconds, and turn the key off. Wait 2 seconds, and turn the key back on (but don't try to start it).
Wait 2 seconds, and turn the key off.
Wait 2 seconds, and then try to start it. If it fires up quicker after doing this, it is definately a problem in your fuel system.

Take care,
~Chris

mike_777 · 07-25-2002, 12:19 AM

If i had a weak pump, wouldn't I notice a decrease in power? Or stumbling? I will test the pressure tomorrow. If its steady while idling, then what should I do?

Thanks
Philip

PKRWUD · 07-25-2002, 02:20 AM

Allow me to elaborate.

In order for a fuel injected engine to fire, the fuel has to be injected, rather than "drawn" in by vacuum and gravity. In order for the fuel to be injected, there has to be sufficient pressure behind it. This is not a problem once the car is running, because the fuel pump is on, but what about when you try to start it? I'll tell you. When you first turn the key on, the ECM sends a signal to the fuel pump relay telling it to power up the fuel pump. If after two seconds, the ECM doesn't receive a signal from the igntion system, telling it that spark plugs are trying to fire, which means that you are trying to start it, it kills the power to the relay, and the fuel pump stops pumping. In a perfect world, drivers would understand this, and would wait for 2 seconds to pass between the time they turned the key ON to the time they turned the key to START, allowing sufficient time for the pump to build up enough pressure to start the engine.

The engineers, however, knew that this was not a perfect world, and that most drivers would just jump in and go straight from OFF to START, and expect it to start right away. To solve this dilemma, they made sure that a healthy fuel system would retain the pressure, even after the key was turned off, and the pump was powered down. In fact, it should retain at least half of the normal idle pressure over night, easing start-up the following day.

Your system is not doing this any longer, which means one of two things is happening. Either there is a leak in the system at the engine end of things, or a failure in the tank end of things. At the engine end, the most likely source for such a leak would be leaky injectors. A bad FPR is also a possibility. At the tank end, there could be a bad or weak check valve, which allows the fuel to bleed back into the tank. Most in tank fuel pumps have the check valve built in, so if that is what was failing, your pump would be at fault, even though it still performs sufficiently to run the engine. Another sign that the pump is getting weak is the amount of time it takes for it to build up sufficient pressure to fire the engine. It should be able to do this in two seconds, tops. If it takes longer, that means the pump is getting weak. It takes a lot more work for the pump to build up the pressure than it does to maintain it while the engine is running, so even if it took longer than 2 seconds to prime the pump so it would start, it would still be able to maintain the required pressure to keep the engine running.

Remember that if the ECM doesn't receive a signal from the ignition system telling it that you are trintg to start the engine, it will shut the pump off, and you will start to lose pressure again. This is why you may have to cycle the key from OFF to ON to OFF to ON a few times before adequate pressure has built up to start it.

SO, if it starts the first time you try to start it, AFTER cycling the key a few times, this verifies it's a fuel system problem, and I will teach you how to determine which part of the fuel system it is that's going bad after you try what I suggested.

Hope that helped.

Take care,
~Chris

Bad89stang · 07-25-2002, 02:28 AM

Dam he's good...

I will be copying this post to my little collection. Thanks Chris!

Conman · 07-25-2002, 06:41 AM

hey chris, love the indepth details

have you started a database of long descriptions so you can cut and paste in a couple weeks when someone else asks the same question?

I think I read a thread just like this a little while back

keep up the good work

sn95gt19 · 07-25-2002, 09:11 AM

mine does the same thing, even if i wait to let the fuel pump prime. only if i crank it for about a second, then all i have to do is click the starter and it starts. its no biggy though, i have learned to live with it.

PKRWUD · 07-25-2002, 01:48 PM

Quote:

Originally posted by Conman
hey chris, love the indepth details

have you started a database of long descriptions so you can cut and paste in a couple weeks when someone else asks the same question?

I think I read a thread just like this a little while back

keep up the good work

LOL. Actually, after more than 3 years of doing this, I just started saving my descriptions about a month ago, but the one in this thread was written on the fly. I guess I should save it, huh? That's my biggest problem. I never think to save them until a couple months later when someone else asks.

Take care,
~Chris

mike_777 · 07-25-2002, 09:56 PM

Hey, I'll try that in the morning. I don't want to try it when I just ran the car for a while so I can get accurate results. By the way the idle at first start is crappy............. idle air control valve?

Philip

Fostang · 07-26-2002, 11:36 PM

Out of curiousity which one is the main supply line on the efi system? The line that hooks up directly to the rail or the one the goes to the regulator first?

Could the problem described mike also make the engine run to rich if it were present??

Fostang · 07-27-2002, 10:55 AM

I tried doing the test mentioned by pkrwud and came up with kind of empty handed because the car started at the second try once again. What I did noticed is that on the SVO if I open to the switch to run the pump and I leave the switch alone and check to see if there is any fuel in the line by pinching the spout sure enough fuel comes out. On the other hand on the efi conversion only some air comes out even if I open the switch 5 times I still come up with just air on the line unless the car is running and thats when fuel does shoot out. Only two things can be to blame fuel pump and fuel regualator or am I missing some piece on my conversion? How do I go about testing which of the two are at fault? I hope all of this made sence to someone.

PKRWUD · 07-27-2002, 12:22 PM

It sounds to me like there is a crack in the hose inside the tank. You will need a fuel pressure gauge to test it. What vehicle is this in, and how is the fuel system plumbed?

Take care,
~Chris

Fostang · 07-27-2002, 08:49 PM

67 Mustang fastback

off original sender I hooked it to the pump from their to the filter to the rail. Then for the return line I drilled and welded tubing to the original sender.

I took out my fuel regulator and somehow an 85 svo fuel regulator made its way onto it. I quickly replaced it with the correct 5.0 regulator which by the way is smaller and now I get out of the hole at the first click.

Now i have a very shaky idle. I checked for vacuum leaks because it sounded like one and there are none present. The smell of raw fuel is present at idle. No leaks in the lines or around the intake.

The idle did go down with the new regulator. I also had to bumb the timing and that helped the idle quality quite a bit. When I pulled the spout to set the timing the idle became worse until I connected the spout back in after I had set the base timing at 14 just wont run right at 10.

Any Ideas of what I should check?

PKRWUD · 07-27-2002, 11:19 PM

What is the pressure at idle, w/ & w/o vacuum? How fast does the pressure bleed down after you shut off the key?

Fostang · 07-28-2002, 09:43 PM

pressure is at 40 psi vacuum disconected.

32 psi with vacuum connected.

Pressure bleeds off fast.

I tried building pressure and pinching the return line then the main line. It held pressure longer while pinching the main line. Therefore I'm thinking its the check valve in the pump. Or a leaky injector? Is their any feasible way of checking to see if there is a leaky injector somewhere? I was thinking imbalance test but how would I be able to unplug the 6,7,8 injectors?

Also about this system had to use a speed density computer for now till I catch a deal on 76 mm mass air. I have a conical filter, intake has been port matched upper-lower lower to heads, Intake tb was oppened for a later install of a 65mm tb, the exhaust side was ported, long tubes with H pipe exhaust all the way back, no cats, 1.77 rrs, no smog pump, timing is at 14, tps is at .96, egr is functional, no canister and the purge valve was pluged.

Just a little basic info about the engine to help you understand what might be the problem and hopefully give me some ideas.

PROBLEM- Car starts up, idles nicely, then begins to surge 1-2 minutes after start up wether it's warm or cold. The surge happens about 5 times between 600-1000 rpms and then idles fine as if nothing were wrong just a smell of raw fuel out the exhaust. Does it again if I turn it off and immidiatly restart it.

Sorry about the long message just trying to get it tunned right. So I can start appreciating all the hard work.

PKRWUD · 07-28-2002, 11:41 PM

Quote:

Originally posted by Fostang
Pressure bleeds off fast.

I tried building pressure and pinching the return line then the main line. It held pressure longer while pinching the main line.

Have someone help you, and pinch of both the supply and the return lines at the exact same moment someone else turns the key OFF. What does the pressure do?

Take care,
~Chris

Fostang · 07-29-2002, 03:05 PM

Haven't done the pinching of both lines because while driving it earlier and down shifting and at the same time accelerating. A very loud back fire came out through the exhaust. It had only back fired mildly once before. What I tried doing was putting in another distriburator I had laying around. It seemed to help the wobily idle and I tried doing the same type of down shift and this time no back fire but the tires broke traction. Hopefully it was a bad TFI or pick up. I'm to the point of really not knowing if changing from carb/C-4 was worth it to EFI/t-5. It seems to lack the same umph it had with a performer intake and 600 cfm carb. In between shifts is where I notice most of the power lost. Seems to take it a while to rev up. Maybe some of the fault is with using the restrictive stock intake and 58 mm TB. Some people tell me it's because fuel injected motors take longer to respond than carb cars.

mike_777 · 07-29-2002, 06:56 PM

Hey,

Well the car seems to start a little easier with the two seconds on and off thing. I also notice a loud buzzing or humming sound from the tank. Is that a sign that I need to get another fuel pump? I heard that was an indication. Thanks

Philip

PKRWUD · 07-29-2002, 11:18 PM

Quote:

Originally posted by mike_777
Hey,

Well the car seems to start a little easier with the two seconds on and off thing. I also notice a loud buzzing or humming sound from the tank. Is that a sign that I need to get another fuel pump? I heard that was an indication. Thanks

Philip

Yes, it usually is. Odds are very much so that your pump is on it's way out.

Take care,
~Chris

mike_777 · 07-30-2002, 01:15 AM

Aight, well I have a half a tank of gas left, so I'll wait until its empty before making the fuel pump switch. What lph would you recommend? Thanks for your help man
Philip

07-24-2002, 11:07 PM	#1
mike_777 Registered Member Join Date: Jun 2001 Location: Independence Posts: 23	No first start? Hey, I was wondering if you guys could help me out. I have a 1990 lx 5.0. Sometimes I try to start the engine it wont fire. But when I do it a second time it does..... Do you folks happen to know why it is doing that? Thanks for all replies. Philip __________________ Famous last words: "Your going to cover me right?"

07-24-2002, 11:39 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	You have a problem in your fuel system. The pressure doesn't build up fast enough (weak pump), or you have a leak some place that is preventing the pressure from remaining after the pump is turned off (leaky injectors, cracked hose near the pump inside the tank). You need a fuel pressure gauge to test the system, and to determine where the problem lies. Next time you try to start it, do this: Turn the key ON, but do not try to start it. Wait 2 seconds, and turn the key off. Wait 2 seconds, and turn the key back on (but don't try to start it). Wait 2 seconds, and turn the key off. Wait 2 seconds, and then try to start it. If it fires up quicker after doing this, it is definately a problem in your fuel system. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-25-2002, 12:19 AM	#3
mike_777 Registered Member Join Date: Jun 2001 Location: Independence Posts: 23	If i had a weak pump, wouldn't I notice a decrease in power? Or stumbling? I will test the pressure tomorrow. If its steady while idling, then what should I do? Thanks Philip __________________ Famous last words: "Your going to cover me right?"

07-25-2002, 02:20 AM	#4
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Allow me to elaborate. In order for a fuel injected engine to fire, the fuel has to be injected, rather than "drawn" in by vacuum and gravity. In order for the fuel to be injected, there has to be sufficient pressure behind it. This is not a problem once the car is running, because the fuel pump is on, but what about when you try to start it? I'll tell you. When you first turn the key on, the ECM sends a signal to the fuel pump relay telling it to power up the fuel pump. If after two seconds, the ECM doesn't receive a signal from the igntion system, telling it that spark plugs are trying to fire, which means that you are trying to start it, it kills the power to the relay, and the fuel pump stops pumping. In a perfect world, drivers would understand this, and would wait for 2 seconds to pass between the time they turned the key ON to the time they turned the key to START, allowing sufficient time for the pump to build up enough pressure to start the engine. The engineers, however, knew that this was not a perfect world, and that most drivers would just jump in and go straight from OFF to START, and expect it to start right away. To solve this dilemma, they made sure that a healthy fuel system would retain the pressure, even after the key was turned off, and the pump was powered down. In fact, it should retain at least half of the normal idle pressure over night, easing start-up the following day. Your system is not doing this any longer, which means one of two things is happening. Either there is a leak in the system at the engine end of things, or a failure in the tank end of things. At the engine end, the most likely source for such a leak would be leaky injectors. A bad FPR is also a possibility. At the tank end, there could be a bad or weak check valve, which allows the fuel to bleed back into the tank. Most in tank fuel pumps have the check valve built in, so if that is what was failing, your pump would be at fault, even though it still performs sufficiently to run the engine. Another sign that the pump is getting weak is the amount of time it takes for it to build up sufficient pressure to fire the engine. It should be able to do this in two seconds, tops. If it takes longer, that means the pump is getting weak. It takes a lot more work for the pump to build up the pressure than it does to maintain it while the engine is running, so even if it took longer than 2 seconds to prime the pump so it would start, it would still be able to maintain the required pressure to keep the engine running. Remember that if the ECM doesn't receive a signal from the ignition system telling it that you are trintg to start the engine, it will shut the pump off, and you will start to lose pressure again. This is why you may have to cycle the key from OFF to ON to OFF to ON a few times before adequate pressure has built up to start it. SO, if it starts the first time you try to start it, AFTER cycling the key a few times, this verifies it's a fuel system problem, and I will teach you how to determine which part of the fuel system it is that's going bad after you try what I suggested. Hope that helped. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-25-2002, 02:28 AM	#5
Bad89stang Registered Member Join Date: Aug 2001 Location: Ft. Worth, TX Posts: 456	Dam he's good... I will be copying this post to my little collection. Thanks Chris! __________________ You're gonna need your seatbelt

07-25-2002, 06:41 AM	#6
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	hey chris, love the indepth details have you started a database of long descriptions so you can cut and paste in a couple weeks when someone else asks the same question? I think I read a thread just like this a little while back keep up the good work __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

07-25-2002, 09:11 AM	#7
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	mine does the same thing, even if i wait to let the fuel pump prime. only if i crank it for about a second, then all i have to do is click the starter and it starts. its no biggy though, i have learned to live with it. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

07-25-2002, 09:56 PM	#9
mike_777 Registered Member Join Date: Jun 2001 Location: Independence Posts: 23	Hey, I'll try that in the morning. I don't want to try it when I just ran the car for a while so I can get accurate results. By the way the idle at first start is crappy............. idle air control valve? Philip __________________ Famous last words: "Your going to cover me right?"

07-26-2002, 11:36 PM	#10
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Out of curiousity which one is the main supply line on the efi system? The line that hooks up directly to the rail or the one the goes to the regulator first? Could the problem described mike also make the engine run to rich if it were present?? __________________ 67' Fastback-Supercharged 4.6 DOHC Cobra, T-56, 8.8 more to come. 67' Coupe-EFI, AOD, 8.8 90 Gt-Supercharged,MAF,TB,1.7's ripper, bassani x, 3.55's, 01' cobras, headers. 89'GT-Supercharged,Heads,Cam,Intake,TB,MAF,power pipe,headers,offroad exhaust,black bullits.

07-27-2002, 10:55 AM	#11
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	I tried doing the test mentioned by pkrwud and came up with kind of empty handed because the car started at the second try once again. What I did noticed is that on the SVO if I open to the switch to run the pump and I leave the switch alone and check to see if there is any fuel in the line by pinching the spout sure enough fuel comes out. On the other hand on the efi conversion only some air comes out even if I open the switch 5 times I still come up with just air on the line unless the car is running and thats when fuel does shoot out. Only two things can be to blame fuel pump and fuel regualator or am I missing some piece on my conversion? How do I go about testing which of the two are at fault? I hope all of this made sence to someone. __________________ 67' Fastback-Supercharged 4.6 DOHC Cobra, T-56, 8.8 more to come. 67' Coupe-EFI, AOD, 8.8 90 Gt-Supercharged,MAF,TB,1.7's ripper, bassani x, 3.55's, 01' cobras, headers. 89'GT-Supercharged,Heads,Cam,Intake,TB,MAF,power pipe,headers,offroad exhaust,black bullits.

07-27-2002, 12:22 PM	#12
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	It sounds to me like there is a crack in the hose inside the tank. You will need a fuel pressure gauge to test it. What vehicle is this in, and how is the fuel system plumbed? Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-27-2002, 08:49 PM	#13
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	67 Mustang fastback off original sender I hooked it to the pump from their to the filter to the rail. Then for the return line I drilled and welded tubing to the original sender. I took out my fuel regulator and somehow an 85 svo fuel regulator made its way onto it. I quickly replaced it with the correct 5.0 regulator which by the way is smaller and now I get out of the hole at the first click. Now i have a very shaky idle. I checked for vacuum leaks because it sounded like one and there are none present. The smell of raw fuel is present at idle. No leaks in the lines or around the intake. The idle did go down with the new regulator. I also had to bumb the timing and that helped the idle quality quite a bit. When I pulled the spout to set the timing the idle became worse until I connected the spout back in after I had set the base timing at 14 just wont run right at 10. Any Ideas of what I should check? __________________ 67' Fastback-Supercharged 4.6 DOHC Cobra, T-56, 8.8 more to come. 67' Coupe-EFI, AOD, 8.8 90 Gt-Supercharged,MAF,TB,1.7's ripper, bassani x, 3.55's, 01' cobras, headers. 89'GT-Supercharged,Heads,Cam,Intake,TB,MAF,power pipe,headers,offroad exhaust,black bullits.

07-27-2002, 11:19 PM	#14
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	What is the pressure at idle, w/ & w/o vacuum? How fast does the pressure bleed down after you shut off the key? __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-28-2002, 09:43 PM	#15
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	pressure is at 40 psi vacuum disconected. 32 psi with vacuum connected. Pressure bleeds off fast. I tried building pressure and pinching the return line then the main line. It held pressure longer while pinching the main line. Therefore I'm thinking its the check valve in the pump. Or a leaky injector? Is their any feasible way of checking to see if there is a leaky injector somewhere? I was thinking imbalance test but how would I be able to unplug the 6,7,8 injectors? Also about this system had to use a speed density computer for now till I catch a deal on 76 mm mass air. I have a conical filter, intake has been port matched upper-lower lower to heads, Intake tb was oppened for a later install of a 65mm tb, the exhaust side was ported, long tubes with H pipe exhaust all the way back, no cats, 1.77 rrs, no smog pump, timing is at 14, tps is at .96, egr is functional, no canister and the purge valve was pluged. Just a little basic info about the engine to help you understand what might be the problem and hopefully give me some ideas. PROBLEM- Car starts up, idles nicely, then begins to surge 1-2 minutes after start up wether it's warm or cold. The surge happens about 5 times between 600-1000 rpms and then idles fine as if nothing were wrong just a smell of raw fuel out the exhaust. Does it again if I turn it off and immidiatly restart it. Sorry about the long message just trying to get it tunned right. So I can start appreciating all the hard work. __________________ 67' Fastback-Supercharged 4.6 DOHC Cobra, T-56, 8.8 more to come. 67' Coupe-EFI, AOD, 8.8 90 Gt-Supercharged,MAF,TB,1.7's ripper, bassani x, 3.55's, 01' cobras, headers. 89'GT-Supercharged,Heads,Cam,Intake,TB,MAF,power pipe,headers,offroad exhaust,black bullits.

07-29-2002, 03:05 PM	#17
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Haven't done the pinching of both lines because while driving it earlier and down shifting and at the same time accelerating. A very loud back fire came out through the exhaust. It had only back fired mildly once before. What I tried doing was putting in another distriburator I had laying around. It seemed to help the wobily idle and I tried doing the same type of down shift and this time no back fire but the tires broke traction. Hopefully it was a bad TFI or pick up. I'm to the point of really not knowing if changing from carb/C-4 was worth it to EFI/t-5. It seems to lack the same umph it had with a performer intake and 600 cfm carb. In between shifts is where I notice most of the power lost. Seems to take it a while to rev up. Maybe some of the fault is with using the restrictive stock intake and 58 mm TB. Some people tell me it's because fuel injected motors take longer to respond than carb cars. __________________ 67' Fastback-Supercharged 4.6 DOHC Cobra, T-56, 8.8 more to come. 67' Coupe-EFI, AOD, 8.8 90 Gt-Supercharged,MAF,TB,1.7's ripper, bassani x, 3.55's, 01' cobras, headers. 89'GT-Supercharged,Heads,Cam,Intake,TB,MAF,power pipe,headers,offroad exhaust,black bullits.

07-29-2002, 06:56 PM	#18
mike_777 Registered Member Join Date: Jun 2001 Location: Independence Posts: 23	Hey, Well the car seems to start a little easier with the two seconds on and off thing. I also notice a loud buzzing or humming sound from the tank. Is that a sign that I need to get another fuel pump? I heard that was an indication. Thanks Philip __________________ Famous last words: "Your going to cover me right?"

07-30-2002, 01:15 AM	#20
mike_777 Registered Member Join Date: Jun 2001 Location: Independence Posts: 23	Aight, well I have a half a tank of gas left, so I'll wait until its empty before making the fuel pump switch. What lph would you recommend? Thanks for your help man Philip __________________ Famous last words: "Your going to cover me right?"

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