My 69 won't start with under 16 gallons- help!

CaliGal · 01-07-2009, 08:40 PM

Hello everybody

This is weird: My 1969 Mustang Grande won't start when the fuel level is lower than around 75%. If already running, she's fine.

I have a new fuel pump and lines. Since the fuel gauge hasn't been working for a decade, I've been in the habit of filling up every time I drive. Since I never drive far, I never noticed this symptom until recently.

Is there something stuck in the tank (the old floater)? Lol

Help! Anyone have any guesses?

bmxmon · 01-08-2009, 04:44 AM

haha, thats really odd. So if you have it filled it would continue to run until its out of gas, but if you let it run until under 75% full then shut it down it wont start back up? Are you trying to start it up again slightly after? Im wondering if your fuel line is running too close to something hot and is cooking the fuel, causing vapor lock. I wouldnt think you have something inside the tank since it would have suction while running but not while off, meaning whatever crap may be inside the tank would stop fuel while running.
I would check your fuel line route and make sure it stays away from hot things, even the intake can heat the line too much.

CaliGal · 01-09-2009, 04:39 AM

Hi Alex

I hadn't thought of the line heating. Thanks!

Here's an update:

Running while less than full was apparently a one-time event (a trip to San Diego). At home, I let it idle until the fuel ran below about 16 gallons, and this time she stalled out-- exactly as if running out of gas. It's like the car only has a 4 gallon tank. When it gets close, I can't rev to hard or there's a cough.

The line does run very close to the manifold (an Edelbrock 4), but since she won't start cold with under 16, I'm guessing that's not it. The new circumstances seem to reintroduce the possibility of something in the tank. Any more ideas or should I just drop it and look for a prize inside?

jim2f · 01-09-2009, 07:51 AM

The pick up tube in the tank has probably came off. Drop the tank and pull out the sennding unit. You should be able to see the pick up.

Be sure to siphon most of the fuel out before dropping the tank.

CaliGal · 01-11-2009, 04:29 PM

Sounds perfectly logical to me. I usually overthink!

At least it's a nice weekend to get a mouthful of old fuel... I should be able to drop it tomorrow and report back. Thanks

bmxmon · 01-11-2009, 06:36 PM

That sounds logical to me as well! Your lucky your in california, we have a couple feet of snow outside plus its really really cold!

CaliGal · 03-05-2009, 07:34 PM

Quote:

Originally Posted by bmxmon

That sounds logical to me as well! Your lucky your in california, we have a couple feet of snow outside plus its really really cold!

My aunt and uncle live in The Twins... they're trying to get me to visit... I know I'll freeze my bippy!

Anyway, sorry it's been so long. Went out on business but finally managed to drop the tank. For being original, I was shocked that it was clean. The pick-up tube was fine. There was, however, some sediment that resembled black sand. Following reassembly, she ran very well for 3 starts. Then the same ol' stuff... stalling out around town. Maybe some sediment still in the carb? I was having to spoon-feed it fuel to get it to start. I'll take it in and have it cleaned... maybe just go back to stock... the Holley has been a pain in the keister.

Mil1ion · 03-05-2009, 07:56 PM

How much of your fuel line is rubber?

Keep it to a minimum.
1) Rubber absorbs heat

2) Rubber breaks down and allows air in causing fuel delivery to the carb problems

jim2f · 03-06-2009, 08:05 AM

When your engine decides not to start, pull the fuel line on the discharge side of the pump. Crank the engine and see if you are getting fuel there. Crank it until it fills a something the size of a coffee can. It should fill pretty quick if you are getting fuel. If no fuel you know its the pump or the lines feeding the pump. If you are getting fuel on the disharge side install a gage between the pump and carb to see what kind of pressure you are getting.

A friend just had to replace all the steel lines from his tank to the pump due to build up of crud in the line. Remove your fuel line at the tank and the inlet side of you pump. blow compressed air through the line...look for sediment and sludge getting pushed out.

The canadian is right. check all the rubber lines too.

01-07-2009, 08:40 PM	#1
CaliGal Registered Member Join Date: Jan 2009 Location: Pasadena CA Posts: 4	My 69 won't start with under 16 gallons- help! Hello everybody This is weird: My 1969 Mustang Grande won't start when the fuel level is lower than around 75%. If already running, she's fine. I have a new fuel pump and lines. Since the fuel gauge hasn't been working for a decade, I've been in the habit of filling up every time I drive. Since I never drive far, I never noticed this symptom until recently. Is there something stuck in the tank (the old floater)? Lol Help! Anyone have any guesses? Last edited by CaliGal; 01-07-2009 at 09:59 PM..

01-08-2009, 04:44 AM	#2
bmxmon Registered Member Join Date: Mar 2004 Location: Minnesota Posts: 950	Re: My 69 won't start with under 16 gallons- help! haha, thats really odd. So if you have it filled it would continue to run until its out of gas, but if you let it run until under 75% full then shut it down it wont start back up? Are you trying to start it up again slightly after? Im wondering if your fuel line is running too close to something hot and is cooking the fuel, causing vapor lock. I wouldnt think you have something inside the tank since it would have suction while running but not while off, meaning whatever crap may be inside the tank would stop fuel while running. I would check your fuel line route and make sure it stays away from hot things, even the intake can heat the line too much. __________________ Alex

01-09-2009, 04:39 AM	#3
CaliGal Registered Member Join Date: Jan 2009 Location: Pasadena CA Posts: 4	Re: My 69 won't start with under 16 gallons- help! Hi Alex I hadn't thought of the line heating. Thanks! Here's an update: Running while less than full was apparently a one-time event (a trip to San Diego). At home, I let it idle until the fuel ran below about 16 gallons, and this time she stalled out-- exactly as if running out of gas. It's like the car only has a 4 gallon tank. When it gets close, I can't rev to hard or there's a cough. The line does run very close to the manifold (an Edelbrock 4), but since she won't start cold with under 16, I'm guessing that's not it. The new circumstances seem to reintroduce the possibility of something in the tank. Any more ideas or should I just drop it and look for a prize inside?

01-09-2009, 07:51 AM	#4
jim2f 65 coupe Join Date: Nov 2005 Location: missouri Posts: 11	Re: My 69 won't start with under 16 gallons- help! The pick up tube in the tank has probably came off. Drop the tank and pull out the sennding unit. You should be able to see the pick up. Be sure to siphon most of the fuel out before dropping the tank.

01-11-2009, 04:29 PM	#5
CaliGal Registered Member Join Date: Jan 2009 Location: Pasadena CA Posts: 4	Re: My 69 won't start with under 16 gallons- help! Sounds perfectly logical to me. I usually overthink! At least it's a nice weekend to get a mouthful of old fuel... I should be able to drop it tomorrow and report back. Thanks

01-11-2009, 06:36 PM	#6
bmxmon Registered Member Join Date: Mar 2004 Location: Minnesota Posts: 950	Re: My 69 won't start with under 16 gallons- help! That sounds logical to me as well! Your lucky your in california, we have a couple feet of snow outside plus its really really cold! __________________ Alex

03-05-2009, 07:56 PM	#8
Mil1ion Registered Member Join Date: Mar 2009 Location: Central Alberta Posts: 7	Re: My 69 won't start with under 16 gallons- help! How much of your fuel line is rubber? Keep it to a minimum. 1) Rubber absorbs heat 2) Rubber breaks down and allows air in causing fuel delivery to the carb problems

03-06-2009, 08:05 AM	#9
jim2f 65 coupe Join Date: Nov 2005 Location: missouri Posts: 11	Re: My 69 won't start with under 16 gallons- help! When your engine decides not to start, pull the fuel line on the discharge side of the pump. Crank the engine and see if you are getting fuel there. Crank it until it fills a something the size of a coffee can. It should fill pretty quick if you are getting fuel. If no fuel you know its the pump or the lines feeding the pump. If you are getting fuel on the disharge side install a gage between the pump and carb to see what kind of pressure you are getting. A friend just had to replace all the steel lines from his tank to the pump due to build up of crud in the line. Remove your fuel line at the tank and the inlet side of you pump. blow compressed air through the line...look for sediment and sludge getting pushed out. The canadian is right. check all the rubber lines too.

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