1995 Mustang GT 5.0 won't start, fuel pressure drops 1 sec after ignition on

[brpavers]

Hey, this is my first post, but I live on these forums when I need to repair my cars. You folks are so generous with advice, so thanks in advance.

My son's 5.0 has been running perfect, but yesterday he cranked it and it ran for 5 secs and then shut down. It seemed like no fuel, so I checked the fuel pressure and it goes to 39 psi when I turn the ignition on and then it goes to 0. The inertia switch is fine. It has a 6 month old Aeromotive 340 lph fuel pump and BBK FPR, so I think those are okay. I just wasted money on the relay module (that has the fuel pump relay) and a new ignition module thinking that the relay was bad or the ignition module was telling the computer to shut down the pump. I don't want to continue wasting money, so can you guys give me some other areas to look.

I am now out of town, but my son is handy with tools and can try some things (He did all the work on a head, intake, cam build while I oversaw and felt pride).

I will follow up on your advice and let everyone know what the outcome is for all to learn.

 

[brpavers]

Sorry. Here's the car info in the signature below.

 

[toyman]

Has the fuel filter been changed? Keep in mind that new or almost new doesn't mean the part hasn't prematurely failed. Pressure should hold to mid 30's with the car running. Try clamping off the return fuel line and check the pressure. Should be about 80 psi and holding. If it doesn't and the filter is good I would suspect the pump.

 

[CC'S95GT]

The PIP sensor inside of the distributor is one of the things that keeps the FP running. It's a common problem with the 5.0's.
A remanned dizzy is about $120 and comes with a warrenty. Just the PIP is about $20 but the dizzy has to be removed and disassembled to replace.

 

[brpavers]

CC, Thanks. I will look into replacing the PIP. I hope I can go the $20 route instead of a new distributor at $200.

Toyman, Thanks. I am thinking the FP is okay because it pressurizes when I switch the ignition, but then it is switched off by the relay. I will run a jumper from the battery to the intertia switch and see if it runs properly with the relay out of the loop. I will go ahead and change the fuel filter, since that's cheap and easy. Your advice about new parts can fail is so true. The 2 new parts that I just installed could be bad. I have seen that happen enough times.

I will wait until I am back home on Thursday. My son may get in trouble with these items and I definitely don't want him messing with the fuel side without some supervision.

 

[Junk94GT]

Any blown fuses? I had a no start situation a couple weeks ago and it had a blown EEC fuse. Turns out it was a shorted fuel injector wire.

 

[brpavers]

Good thought. I checked the FP and EEC fuses first. All good.

Thanks

I am jumping the FP off the battery in the am, then checking everything electrical. After that i will be tackling changing the pickup in the dizzy. This will be a major operation though. I have to pull the dizzy and to do that, I have to remove the Trick Flow intake because of a lack of 1/8 inch of in clearance between the dizzy body and the intake. I should have ground the intake down when I discovered this during the cam install. The plumbing and reworking it took to get the intake on the 1994-95 set-up is FUBAR. I will take some pics.

 

[68eleanor]

Do not buy one of those new distributors from Oriellys, One of those about cost me an engine, the shaft is not hardened engough, my oil pump shaft shredded one, fix your stock one or buy a remanufactured factory one, make sure you replace the inline can filter in front of the tank, I used a wix, if you are still running stock fuel lines

 

[brpavers]

Okay, so I have been trying to avoid pulling the distributor because I just haven't had the time to commit this weekend. I think I will take it to the shop if thats the issue.

I sprayed some electrical contact cleaner on the PIP and I got the car to start after it would not hit at all for days. When it did start, the engine shot up to 5000 rpm, whistling like a steam engine, and then it went down to 900 rpm for a second and then died. started it again and it did the same thing. There was gray fuel smelling smoke out the back of both pipes.

I checked the TPS voltage and the reference in is 5.0v but I can't get a signal back. Also, the radiator fans do not automatically switch on with the key on like they used to (I have the air pump off and had to reroute the belt, so the water pump turns backward and because of that had to take the thermo out and have the fans run at all times).

Anyway, I am thinking its the PCM or the SCT chip that causing the problem. I going to haul it to a shop and let them look at it while I am out of town. I hate working on a car when it won't run. I especially hate to change things when its not running. You can't get so far off base and then never get it back.

I will report back when I see what the solution is, hopefully. I hate it when people start a thread to resolve an issue, get suggestions from 10 people and then do not report back what their solution was, even if it was to push it off a cliff. Don't leave us hanging like that.

 

[CC'S95GT]

You should be able to get the water pump to turn properly without the air pump by just looking at the routing better. Smooth sideof the belt to the smooth side pully and grooved side of the belt to the grooved pully.
The whistleing sounds like a vacuum leak.
If your going to take it to the shop you may as well buy a remanned dizzy and swap that out your self. the diagnostics is gonna run about $90 before they replace anything.

 

[rz5.0]

he is right your water pump should still run the same direction regardless of the air pump..

 

[brpavers]

Well the mechanic got to work on the car and found there were 3 vacuum leaks: 2 in the CAI and 1 in the spacer between the throttle body and the Trick Flow intake. Good call CC95. After he buttoned those things up he drove the car and said it was running strong and he pulled it in his garage until my son could get by to pick it up. This morning he tried to crank it to back it out of the garage and it wouldn't start. He diagnosed a fuel issue and put a fuel pressure gauge and on it and it goes from 37 psi to 0 to 24 and he says the fuel pump is going out. I have a Krugen Torker 340 lph fuel pump heading that way. I hope that fixes it. What are the odds of 3 vacuum leaks and a fuel pump going out all at the same time. My son babies the car. Its spotless and the hood goes up every night so that he can make sure everything is in order.

I will let you guys know the results.

 

[toyman]

Well the mechanic got to work on the car and found there were 3 vacuum leaks: 2 in the CAI and 1 in the spacer between the throttle body and the Trick Flow intake. Good call CC95. After he buttoned those things up he drove the car and said it was running strong and he pulled it in his garage until my son could get by to pick it up. This morning he tried to crank it to back it out of the garage and it wouldn't start. He diagnosed a fuel issue and put a fuel pressure gauge and on it and it goes from 37 psi to 0 to 24 and he says the fuel pump is going out. I have a Krugen Torker 340 lph fuel pump heading that way. I hope that fixes it. What are the odds of 3 vacuum leaks and a fuel pump going out all at the same time. My son babies the car. Its spotless and the hood goes up every night so that he can make sure everything is in order.

I will let you guys know the results.

For $25 I would buy a code reader. You really need to see what the ECU is logging for troble codes. I suspect the vacuum leaks have been there ever since the CAI was installed. You pointed to a fuel pressure issue in your first post.

 

[brpavers]

Help

Toyman, Thanks for the advice. I read the codes and got the 511 code because I have the SCT chip in the PCM. That's all you get with a chip and you can't get anymore info than that.

I got the car back from the mechanic and he has thrown his hands up. He installed a new pump and that was not the problem. It back to square 1. After the car sits it won't start. When I turn the ignition on, the fuel pump starts, runs a second, I hear a click from the FP replay in the CCRM and then the FP shuts off and the FP drops to 0. To start the car, I have to crack the throttle, and turn the ignition on and off. This allows fuel to fill the combustion chamber. After several minutes of this, I then open the throttle a little more while starting and it cranks, but it will not maintain an idle until it warms up. After it warms up, it runs fine until I let it sit again for a few hours, then all the fuel in the combustion chamber bleeds down and there's nothing to combust. Start the on-off process again. What a PITA.

On top of this, the electric fans do not come on with the computer. I ran a jumper to the fan and have a toggle switch to cut the fans on and off, NASCAR style.

With both of these issues going on at one time, I am thinking its the PCM or it could be the temperature sensor, although that is a new piece. I may have to get a remanned PCM and reinstall the chip. It also could be the CCRM that I just installed at the beginning of this is bad. If that's the case I will tie it to a brick and return it through the front window of the parts store I bought it from.

 

[brpavers]

Help

Toyman,Thanks for the advice. I read the codes and got the 511 code because I have the SCT chip in the PCM. That's all you get with a chip and you can't get anymore info than that. I got the car back from the mechanic and he has thrown his hands up. He installed a new pump and that was not the problem. It back to square 1. After the car sits it won't start. When I turn the ignition on, the fuel pump starts, runs a second, I hear a click from the FP replay in the CCRM and then the FP shuts off and the FP drops to 0. To start the car, I have to crack the throttle, and turn the ignition on and off. This allows fuel to fill the combustion chamber. After several minutes of this, I then open the throttle a little more while starting and it cranks, but it will not maintain an idle until it warms up. After it warms up, it runs fine until I let it sit again for a few hours, then all the fuel in the combustion chamber bleeds down and there's nothing to combust. Start the on-off process again. What a PITA.

On top of this, the electric fans do not come on with the computer. I ran a jumper to the fan and have a toggle switch to cut the fans on and off, NASCAR style. With both of these issues going on at one time, I am thinking its the PCM or it could be the temperature sensor, although that is a new piece. I may have to get a remanned PCM and reinstall the chip. It also could be the CCRM that I just installed at the beginning of this is bad. If that's the case I will tie it to a brick and return it through the front window of the parts store I bought it from.

 

[toyman]

Pull the vacuum line from the FPR to see if there is ansign of gas present. There shouldn't be. It's my understanding that the SCT chip should not affect the testing for DTC's. You might want to try the paperclip technique for the test.

 

[rz5.0]

I use to have a act chip and still got codes out of it 511 included...

 

[rz5.0]

Have you tried pulling the chip out..

 

[brpavers]

RZ, I won't damage the chip by pulling it will I. Its just plug and play right. I asked Bob Kurgan who programmed it, but he hasn't got back with me.

 

[brpavers]

Toyman, There is a gas smell in the FPR vacuum line. Why would this cause the FP to cycle off even before the engine turns over. Shouldn't the FP stay on for 20 sec or so. If you think its the FPR, its still under warranty and I can call BBK and get a return authorization number and get one shipped in for free, assuming BBK agrees its bad.

I have $600 invested in the SCT Chip and the dyno tune. Can I just unplugg it.