Enging Shutdown Problem..Help!

[Lashbrook27]

I have a 1990 Mustang GT. The engine is shutting off and the fuel pump relay starts to open and close very quickly. I jumped the power in the EEC Power relay to rule out a bad ignition switch, and EEC relay. After jumping it I let it run for several miniuts when the same thing happened. The fuel pump relay started opening and closing really fast then the engine died. Has this happend to anybody before? Is the computer cycling the system like an initial prime, or is the computer starting to take a dump? There are a lot of things that are powered off the EEC relay, could any of those things cause this?

...1990 Mustang GT/stock block & cam/GT40P Heads/ford racing headers/bbk high flow h-pipe w/cats/40 series flowmasters dumped/cobra intake/73 c&l MAF/3.73's/24lb injectors/bbk cold air fender mount intake/msd cap & rotor/msd 8mm wires/(soon to have MSD 6AL, not hooked up)/Automatic w/shift kit & cooler............

[Dog5ohfun]

Try changing your fuel pump relay. You didn't say if you have tried that yet. Relay don't always quit woking all at once. Sometimes they are intermittent. Hope this helps.

[Lashbrook27]

The fuel pump relay is good. i get two relays that start clicking. The fuel pump relay and the WOT relay. If I take out either one, I still get the problem. Leaving one of them in helps me to hear the problem. Now if I turn the key on without starting soon after the relays will start clicking. When this happens the fuel pump kicks on. Tonight to rule out a bad fuel pump I am going to cut the wire coming out of the computer going to the fuel pump, and remove the fuel pump relay. If the problem goes away I will drop the tank. The fuel pump was serviced recently when the car came out of storage. The WOT relay is a normally closed relay and the computer opens it when the A/C is on at full throttle. When I turn the key on this relay clicks. It shouldn't do that. Something is shorting out.

[Lashbrook27]

How was doing business with DSS? I am waiting for a quote from them as we speek.

[Dog5ohfun]

I didn't deal with them directly. My local shop ordered it for me. Sorry I couldn't offer more info on DSS.

[rivs]

Im having exactly the same problem on a 90 gt. Any updates on this will be appretiated

[Lashbrook27]

I replied to you private message but to update for everyone else who may be interested. I was having several problems with my car. The first problem was a starting problem. I fixed that issue first because it was my first problem. Once I fixed that I put the code reader on it. I was getting a code 22 (MAP/BP sensor). Since this only reads atmospheric pressure I picked up a new one. Atleast that is all it does my 1990. Replacing that fixed my other problem. I am guessing due to the bad signal from the BP sensor the computer was going crazy. I hope this helps anybody with a similar problem. I picked up the code reader from Autozone!!

[rivs]

thanks a lot for responding, Did you buy a stock map or you upgraded to 2 bar?? Ill ask a buddy of mine for his to test it on mine.

[Lashbrook27]

On my 1990 it reads barometric pressure. I picked it up from a local autozone, stock replacement. Not sure why a bad reading from this cause my WOT and fuel relays to start clicking.

[rivs]

What was your starting problem?? I installed another MAP sensor, and still the same, also checked the under seat realay and the WOT relay and they are good. removed the ecm and cleaned contacs, jumped the ECM relay and still problem, im going crazy with this. I need an exorcist!!!

[Lashbrook27]

My starter relay was staying closed, so the starter would stay cranking after the engine was running. I had my starter checked/checked out okay but the bearings were shot/replaced that. Didn't know if ignition switch racall was done, so I picked up a new one. My contacts in my neutral/park safety switch didn't sound good so I picked that up also. There was an aftermarket securty system installed on it before I purchased the car. There were all kinds of splices under the dash, so I removed all of that crap. My starting problem is solved. Is your computer giving you any codes?

[Lashbrook27]

I wouldn't have replaced the MAP sensor unelss you were getting a code 22. Those things don't typically go bad. start with checking for codes. If you don't have a reader pick one up from autozone. It is pretty cheap and easy to use.

[rivs]

you know what?? it also happened to me that when i shut engine off it kept cranking, in a way that i had to put it in gear and let the clutch out and step hard on brakes to be able to shut it off. But it happened only a couple of times, not anymore. KOEO i get a constant 85, i can't do a KOER because it starts bucking and missfiring before it reads anything, and shuts down the engine. Code 85 is canister purge circuit failure, I eliminated all smog equipment and the plug between Engine coolant temp sensor, and idle speed control, wich is for canister purge solenoid is hanging loose. Ill try to find one but i dont understand why it shorts everything out!!