help fast fuel pump relay problem

The relay is a small box, about a 1 1/4" cube without the socket.. It is located under the driver's seat in 86-91 cars and under the MAF in 92 and later cars. If you don't have big arms, it will take about 2 minutes to replace.

If that doesn't fix it, plan on having the car towed to some place you can work on it safely.

Judging by your user profile, I'm assuming the problem is with the 88 GT. The previous post (by JR) is 100% right Make sure you bring a ratchet set with you to pop out the drivers seat. Trying to remove the relay with seat in place is a pain in the A$$. Only 2 nuts and 2 bolts to yank the seat. Disconnect lumber support harness and you should be good to go.

Slo, I notice in your post that you had a problem with the car starting before, let me run my situation by the group and see what "pops up". I also have a 5.0 that will not start. My previous set up required a T-Rex fuel pump backed up by a 155 lph in-tank fuel pump. I have recently sold that engine set up and dropped a stock 5.0 back in the car. The fuel set up now is the 155 lph fuel pump with the T-Rex removed. After the motor swap, the car ran fine but had a problem with the battery dying after being left sitting for a day or two. On the way home from my buddies house where the engine swap took place, one of the O sensors came out of the x-pipe and like a dumb-a$$ I drove on home. Sure enough, after a couple of days the battery was dead and I jumped it off with my schauer charger/jumper which got the engine to turn over but not start.

Sorry for the lengthy background but this brings us to where I am now. The engine will crank over but not start. If I hold the accelerator to the floor, it will occasionally sputter and try to start, but that is all. One strange anomaly is the fact that the fuel pump runs continuously with the key in the on position. I was under the impression that once the fuel system was pressurized the pump shut off (either by timer or a pressure switch).

Looking for input,

Thanks,
Dave

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) Coil
B.) TFI module
C.) PIP sensor in distributor
D.) ECC relay next to computer
E.) Fuse links in wiring harness
F.) Ignition switch
G.) Computer

2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.
Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t ,then it is a computer or timing issue: see Step 4.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe -& hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

4.) Spark & fuel OK.
A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off only likely if the engine has been worked on recently).
D.) Firing order off: HO & 351 use a different firing order form the non HO engines.

jrichker,

Thanks for the suggestions, I will give those a try and reply back.

Mr. P

Progress report:

Spark: check
Starting fluid: Engines starts with starting fluid.

That leads me to the fuel management portion of the post, I get fuel pressure to the schrader (sp?) valve, but I am not sure it is enough. Right now I am leaning toward the fuel pressure regulator as the engine is used and I am unsure how long it set on a pallet out of a car. However, I do not get any fuel in the vacuum line to the regulator when I check it and that is causing doubts. The fuel pump never stops running, if that is an indicator of anything.

Where now?

Thanks.

The good news:

The car runs, kind of.

The bad news:

At idle it runs like $hit! I checked the TPS and its voltage is running around 4.25 with no adjustment able to be done. I swapped the TPS, same results. When the car is brought gradually off of idle to around 3500-400 rpms, it runs good.

The check engine light is on, but following the procedure in the manual. which I have used before on another setup, I am unable to pull codes with either the sweep meter method or the check engine light flashing method.

I still have the issue with the fuel pump never shutting off. I hooked up a fuel pressure tester kit and it read 39 lbs and stayed there. With the engine running and the regulator connected it fluctuated as expected.

I'm not sure if these all point to a common problem but the fact that I cannot get codes, the voltage irregularity on the TPS, and the fuel pump not shutting off all lead me to think it may be the computer.


HELP! : )

Thanks.

Since were talking about fuel pumps,in my 87gt when it gets cold outside my fuel pump wont kick on but when its warm out no proplem.Any ideas?