I have an 87 305 5.0 TPI. I have been searching all over the threads for a week or so and have done many things so far, but can not get the car to start and stay running. I will be replacing the fuel pump relay tomorrow just to see. I have so far replaced the plugs, wires, cleaned the injectors. I have also checked for any vacuum leaks, checked the fuel pressure regulator. The pump was replaced last winter and has only been started twice since then. The car was running 2 months ago when it was started last. I went to try to start it a few weeks ago and will just turn over and not fire. I don't have a gauge, but I think it has low fuel pressure. It just kind of dribbles out on the check valve. Even when cranking the engine over. I have sprayed starter fluid in the plenum and it runs with that till it burns off and as soon as you hit the throttle it will die right away. Any advice would be appreciated.

 

Until you check the pressure and confirm what the problem is ,then just throwing $$$ at it.
There are other causes of no / low fuel pressure than the pump itself

How can you do the fuel regulator pressure tests without a gauge ?

 

Maybe I should restate some of what I said I guess. I never said I did any fuel pressure regulator tests. I checked the fuel pressure regulator diaphragm for cracks like another thread suggested. When I press the check valve for the fuel rail with the key on, off, or turning the car over it does not spray out and only seeps out. I would assume if there was pressure it would spray out. If I had a gauge and it read low pressure. What would I do from there? I would guess maybe the fuel pump relay? I didn't say it was a bad fuel pump. I just wanted to give who ever reads this all of the information to date as to what has been messed with and replaced. Along with all of the symptoms. I am not very familiar with TPI systems.

 

I assumed from your statement that you had tested the reg for leaks.
If the reg is leaking and bleeding off the pressure back to the tank you will have no line pressure at the test point.

Ist test would be to check if the pump is actually running ?
If your OP switch ( pump backup system ) is functional, the pump should run as soon as the OP is over 4psi while cranking;
independent of anything the relay is doing ( or not )

Check for relay operation ; key on
Check for power available at relay ,there are 2 power wires from different sources
Check pump fuse ( under hood ? ); supplies power through both the relay and the OP switch to the pump .
If it blows you have no power on either the main or backup pump circuits

 

Remember, if the regulator is leaking internally the gas goes into the crank case by way of the vacuum lines and into the oil pan so smell your dipstick for gas.
If you smell a strong gas ordor that then change the regulator and change the oil. Run the car for a couple of minutes and change the oil again. Any gas in the oil pan will kill the engine.

The problem is usually the gas pump in the tank. Just lay under the rear of the car and have someone turn on the key. NO sound means the pump went bad. Gas pumps go bad from sitting around but relays usually don't.

If there is no sound and your still not sure it's your gas pump gone bad just buy a new one and wire it in the rear plug above the rearend housing. I keep an extra gas tank wiring harness just for this purpose. The pumps are cheap but changing them is not.

When the pump gets replaced the regulator may not be able to cope with the extra pressure that it didn't have before and still spring a leak internally so watch out for that.

 

Thanks guys for the suggestions. I am looking at the car right now. I got a fuel pressure gauge from the auto parts store too. The relay was not the problem, but I can return it. The fuel pump was new from winter of 2012. I do not know the brand. It was changed by the previous owner. He just could tell me it came from Autozone. It has only been started twice since then. I did smell the dipstick and I don't seem to smell gas. Just old oil.

 

I've been looking at your diagram. If that red lead is the one going into the relay labeled MAF Power it is not getting power at all. The orange lead however is.

 

Ok red lead is working. I found on a diagram it goes to the pump prime and it works when cranking the motor over. So it looks like I need to find a way to test the fuel pump before I go ahead and tear that apart again.

P.S. or could this be a faulty oil pressure switch?

 

I have another update. Ran tests of the fuel pump and it appears to not be running. Ran the jumper test and directly put power to it and nothing from it at all. So it looks like the problem is the new fuel pump went bad. Would there be another reason or something else to check?

 

Time to drop the tank to replace the pump I suspect

or do the trap door mod for easy access

https://www.thirdgen.org/forums/fabr...mp-access.html

 

I was afraid of that lol. I will probably just go ahead and drop the tank instead of the trap door, but we will see. Probably depends on how I feel about it when it comes time to doing the job. Thanks for the help.

 

I was able to do it without dropping the rear end, but it is REALLY hard. Highly recommend the trap door.

 

I'm still considering it, but really really hesitant on cutting up the floor.

 

I didn't want to cut my floor up either. And I didn't want to drop the rear. It takes a lot of body contortion and stretching to get in there, but it is possible (depending on your physical size). You could try that first. Nothing much to lose by trying it first. Unless you have a short temper. Then don't even think about it.

 

If you do drop the tank be sure to test it before you put everything back together. Some problems may include Oring leak at the top of the tank pickup screen catching on the float not allowing the gas gauge to work just to name a couple.

You may also find the tank and pickup assembly is full of rust and corrosion that needs to be cleaned out. That's the #1 killer of gas pumps IMO.

 

I will check that stuff before I put everything back together. I was kind of curious about the condition of the sending unit. Just seems odd that this new pump already went bad.

 

So the Sending unit looks good. I need to test the old pump yet, but I have the new pump on (Delphi brand) and the sending unit ready to put back in. Should have it done in an hour after I get off work Today. The rubber on the other pump was falling apart. I was told by the previous owner that it was purchased new 4 years ago and then put in last winter (airtex brand). Then the car was only started a few times after that. Granted it did sit with not much gas in it, but I would have though a new pump would last longer than that.

 

New fuel pump and car runs great again.