Fuel pump keeps priming - no start (still!)

[lahrs37]

OK, so here is another wrinkle in my month long quest to start my car. So after what I thought was a successful first start, which occurred after I replaced the IAC I was sure I was done with that issue and just needed to fine tune my timing with a light. Nope. Now I cannot start it at all. The fuel pump kicks on when I key on and stays on. The engine will not catch at all. I thought it might be the old PCM so I pulled it and inspected it. Everything looked fine. Before reconnecting it, I keyed on again and the fuel pump was STILL running. Aha, I thought, it must be a bad relay. I checked the part numbers on the other relays and switched in a different one and SAME thing. My next move is to replace the fuel pressure regulator unless anyone has a better idea.

[GSides9]

I just went out and listened to my 2002 Ford van and the fuel pump runs non stop as long as the key is on. My Yukon is different, it runs until it builds pressure and stops. I think Fords send full pressure to the fuel rail and return the extra pressure to the fuel tank via the regulator at the end of the fuel rail.

Glen

[michael everson]

There is something wrong with your ECU if your pump keeps running. If this is a 87-93 5.0, there is no fuel pressure sensor. The pump just runs for a short time to pressurize the rails. Check all your grounds. There is a big one near the ECU. I would start with a test light to see if the pump is staying on when your cranking it. Also a fuel pressure gauge on your rail to check for pressure. If you have pressure then its electrical. Also, I know this sounds strange, but make sure you have the ignition switch wired correctly. If you have the IGN and ACC backwards, it will only start by pure luck. This can be tested by turning the key on and jumping the solenoid to see if it starts.
Mike

[wareaglescott]

Are you confident fuel is in fact getting to the motor?
I know that sounds like a strange question but I had an issue where the pump was running and fuel was not leaving the tank because a hose on the pump that was internal to the tank came unclamped. The pump was just shooting the fuel back into the tank. Im sure your setup is different but if you have a way to verify the fuel is getting all the way to the motor maybe try that. My first step was to see if fuel was exiting the fuel filter and when it wasn't I started working backwards until i determined it was never leaving the tank.
Good luck!

[GoDadGo]

Man I wish I could help, but this one is way over my head.
Good Luck & Don't Get Discouraged!

[lahrs37]

There is something wrong with your ECU if your pump keeps running. If this is a 87-93 5.0, there is no fuel pressure sensor. The pump just runs for a short time to pressurize the rails. Check all your grounds. There is a big one near the ECU. I would start with a test light to see if the pump is staying on when your cranking it. Also a fuel pressure gauge on your rail to check for pressure. If you have pressure then its electrical. Also, I know this sounds strange, but make sure you have the ignition switch wired correctly. If you have the IGN and ACC backwards, it will only start by pure luck. This can be tested by turning the key on and jumping the solenoid to see if it starts.
Mike

Even with the ECU disconnected, the fuel pump keeps running when it is keyed on. Can you explain this a bit more "This can be tested by turning the key on and jumping the solenoid to see if it starts." Thanks!

[lahrs37]

I just went out and listened to my 2002 Ford van and the fuel pump runs non stop as long as the key is on. My Yukon is different, it runs until it builds pressure and stops. I think Fords send full pressure to the fuel rail and return the extra pressure to the fuel tank via the regulator at the end of the fuel rail.

Glen

Supposedly on Fox bodies the fuel pump is just supposed to prime for a couple seconds until pressure has built up, then turn off. Thanks for checking though!

[lahrs37]

Are you confident fuel is in fact getting to the motor?
I know that sounds like a strange question but I had an issue where the pump was running and fuel was not leaving the tank because a hose on the pump that was internal to the tank came unclamped. The pump was just shooting the fuel back into the tank. Im sure your setup is different but if you have a way to verify the fuel is getting all the way to the motor maybe try that. My first step was to see if fuel was exiting the fuel filter and when it wasn't I started working backwards until i determined it was never leaving the tank.
Good luck!

I can actually hear the fuel at the rail so I don't think that is the issue, but I will add it to the list of things to check if nothing else works!

[lahrs37]

Man I wish I could help, but this one is way over my head.
Good Luck & Don't Get Discouraged!

Thanks! I have called in some reinforcements. A local FFR builder and my father-in-law are coming by this weekend to see if they can help too. I am not giving up!

[GSides9]

I hate giving wrong info. Thanks Mike for covering my mistake.

Glen

[lahrs37]

There is something wrong with your ECU if your pump keeps running. If this is a 87-93 5.0, there is no fuel pressure sensor. The pump just runs for a short time to pressurize the rails. Check all your grounds. There is a big one near the ECU. I would start with a test light to see if the pump is staying on when your cranking it. Also a fuel pressure gauge on your rail to check for pressure. If you have pressure then its electrical. Also, I know this sounds strange, but make sure you have the ignition switch wired correctly. If you have the IGN and ACC backwards, it will only start by pure luck. This can be tested by turning the key on and jumping the solenoid to see if it starts.
Mike

OK, so I verified that the ignition switch is wires properly. I will look into getting a fuel pressure gauge to check that.

[rich grsc]

I think your computer is shot, the fuel pump should stop have a few seconds. Fuel pressure or not, it shouldn't keep running.

[lahrs37]

I think your computer is shot, the fuel pump should stop have a few seconds. Fuel pressure or not, it shouldn't keep running.

I ordered one a few days ago just in case. Pretty much everything from my donor engine has been complete junk other than the block itself.

[GoDadGo]

Worse Case Scenario:

You can ditch the E.F.I. and go totally old school; however, I don't recommend giving up until you can get a certified mechanic or Factory Five Guru (Master Builder) to go over your systems.

It Ran Before So It Will Run Again!

This truth will be self-evident, but only after you've aggravated your neighbors from driving that crazy Go-Kart around your home.

Steve

[blitzkreig baja]

Hey lahrs37,

I was looking at the "stangnet" forum and saw several posts by a jrichker. one was a check list for EFI 5.0's not starting. I think it was titled "help won't start??" Might help. Hope you figure it out.

[lahrs37]

Hey lahrs37,

I was looking at the "stangnet" forum and saw several posts by a jrichker. one was a check list for EFI 5.0's not starting. I think it was titled "help won't start??" Might help. Hope you figure it out.

Thanks! I saw those same posts. I am working on the fuel pump constant running problem first. If that doesn't solve the start issue, I will incorporate that info into my plan.

[Jeff Kleiner]

Here's a longshot on the constantly running pump. If the "fuel pump" terminal on the diagnostic plug is grounded the pump will run anytime the ignition is on. Is it possible that wire got pinched or grounded inadvertantly?



With that said though understand that the fuel pump running constantly will not keep it from starting. I'm betting on a TFI/PIP problem or bad ECU. The way it SHOULD work is that when you turn the key on the pump runs for a couple of seconds to charge the system then shuts off until it sees a "crank" or "run" signal from the PIP. If the TFI module or PIP has failed it could be sending an erroneous signal to the ECU to keep the pump running---at the same time the failure could be disabling the ignition. A bad ECU could result in the same conditions. Do you have spark while cranking? Check it and let us know.

Jeff

[Joee]

I was able to get a spare working A9L to swap yours out with for testing. Unfortunately it needs to come home with me but, it will answer many potential problems you are having.

[lahrs37]

Here's a longshot on the constantly running pump. If the "fuel pump" terminal on the diagnostic plug is grounded the pump will run anytime the ignition is on. Is it possible that wire got pinched or grounded inadvertantly?



With that said though understand that the fuel pump running constantly will not keep it from starting. I'm betting on a TFI/PIP problem or bad ECU. The way it SHOULD work is that when you turn the key on the pump runs for a couple of seconds to charge the system then shuts off until it sees a "crank" or "run" signal from the PIP. If the TFI module or PIP has failed it could be sending an erroneous signal to the ECU to keep the pump running---at the same time the failure could be disabling the ignition. A bad ECU could result in the same conditions. Do you have spark while cranking? Check it and let us know.

Jeff

Good info! I will be able to get back into the garage tomorrow and I will check that out.

[lahrs37]

I was able to get a spare working A9L to swap yours out with for testing. Unfortunately it needs to come home with me but, it will answer many potential problems you are having.

That is awesome! I have already put an order in for a refurbed one from Pep Boys in case that is the issue.

[Norm B]

I think Jeff is on the right track. The ECU provides the ground signal for the fuel pump relay. There's no way the pump should run without the ECU connected unless the wire from the relay to the ECU is shorted to ground. This still doesn't explain the fail to start problem.

I would pull a spark plug, check its condition, attach the ignition wire and place the plug in a grounded position on the engine. Get someone to turn the engine over while you watch the plug for spark. While you've got your assistant handy, use a mechanics stethoscope (or a dry stick up against your ear) to listen to the injectors. You should be able to hear them clicking a when the engine is turning over.

Seems like multiple issues going on and it's going to take time and patience to solve them one at a time.


Wishing you luck

HTH

Norm

[Jeff Kleiner]

...I would pull a spark plug, check its condition, attach the ignition wire and place the plug in a grounded position on the engine. Get someone to turn the engine over while you watch the plug for spark...

No offense Norm but---Please do not do it that way! Don't leave the plug out while checking for spark unless you are certain that the fuel system is disabled; either use another plug or stick a metal screwdriver or ??? in the plug wire terminal and hold it about 1/16" away from the block or good solid ground to watch for spark. The risk of leaving the plug out is that if fuel is being injected into the cylinder this atomized fuel will be sent out of the hole on the compression stroke...if you are holding the plug nearby and make a spark things could get ugly really quick. Be safe!

Jeff

[Norm B]

None taken Jeff. I should have been more clear with my directions. I assumed that no one would have the plug anywhere near the open hole when doing a test. Yes, I know what happens when you assume!

I usually use plug 4 or 8 and have a lead with alligator clips for grounding the plug a long ways away from the hole. Hope that's more clear. Play safe everyone!

[michael everson]

It might be that the RF harness has its own fuel pump circuit and is independent of the ECU.
Mike

[CraigS]

It might be that the RF harness has its own fuel pump circuit and is independent of the ECU.
Mike

Although I haven't checked this specifically, two friends building MkIVs have mentioned fuel pump wires in the harness.

[phileas_fogg]

Mike & Craig are correct; Rev N of the Ron Francis harness (provided with my complete kit the summer of 2015) includes a fuel pump circuit.

So Lahrs, if you didn't do anything to make the ECU control your fuel pump it seems perfectly normal for the fuel pump to run continuously from the time you key the car on until you key the car off.


John

[lahrs37]

Mike & Craig are correct; Rev N of the Ron Francis harness (provided with my complete kit the summer of 2015) includes a fuel pump circuit.

So Lahrs, if you didn't do anything to make the ECU control your fuel pump it seems perfectly normal for the fuel pump to run continuously from the time you key the car on until you key the car off.


John

Ok, so not to sound stupid, but how do I make the ECU control my fuel pump?

[michael everson]

It really doesn't need to. Its perfectly fine the way it is. Somewhere in the ECU wiring is a fuel pump trigger. Pin number 22 grounds a relay to turn the pump on.

Mike

[lahrs37]

It really doesn't need to. Its perfectly fine the way it is. Somewhere in the ECU wiring is a fuel pump trigger. Pin number 22 grounds a relay to turn the pump on.

Mike

Hmmm, that kind of gets me back to making sure I have all the right grounds. I have a big list of things - thanks to this thread - to check this weekend. I also have fresh eyes coming Saturday morning. I will report in after I have tried a bunch more stuff! Thanks y'all!

[lahrs37]

So it would probably be a good idea to have a BAP sensor.... Oh the shame! Thanks Joe for the help!! It would also be helpful if I read the wiring instructions correctly and spllced in the fuel pump wire from the front harness. Sometimes you just really need another set of eyes and some actual knowledge and experience! The BAP sensor should be in this morning. I will keep you all posted. Thanks for all of the input everyone!

Video before figuring out the BAP: https://www.youtube.com/watch?v=QHjaMvJUiko

[wareaglescott]

Hey you got it running! Progress. Congrats!

[blitzkreig baja]

Sweet!! Shes a runner.

[lahrs37]

OK, quick update: I installed the BAP and that seem to have fixed the popping and backfiring. It still dies right after I hit the throttle. I tried to wire in the fuel pump wire from the front harness, but I totally cannot figure out where it goes. I will call Ron Francis on Monday. Then I threw out my back. So I am out of commission for a bit.

[Mark Dougherty]

glad the car is running
feel free to call again anytime you need help

[RickP]

So it would probably be a good idea to have a BAP sensor.... Oh the shame! Thanks Joe for the help!! It would also be helpful if I read the wiring instructions correctly and spllced in the fuel pump wire from the front harness. Sometimes you just really need another set of eyes and some actual knowledge and experience! The BAP sensor should be in this morning. I will keep you all posted. Thanks for all of the input everyone!

Video before figuring out the BAP: https://www.youtube.com/watch?v=QHjaMvJUiko

She's alive. Congrats.

[GoDadGo]

Didn't I Tell You That If It Ran Before It Would Run Again?

A Big Congratulations From The Swamp Lands Of Louisiana!

[lahrs37]

glad the car is running
feel free to call again anytime you need help

Thanks Mark! I probably will.

[lahrs37]

Didn't I Tell You That If It Ran Before It Would Run Again?

A Big Congratulations From The Swamp Lands Of Louisiana!

Heck yeah! Thank goodness for this awesome community for putting me on the right path!

[Vette1972]

Persistence is all powerful! Great job. Len

[Jeff Kleiner]

Have you put a timing light on it yet? If not that is what you need to do next.

Jeff