The Ole' FPR issue

[SnowLover]

Okay- I used the search program and read the FPR and Fuel Pump Relay posts. My problem is hard starting. Yes, I understand it's a Ford and it's normal to be a hard starting pain in the butt. I have been told it's the fuel
filter, but I doubt this because there isn't much flow during start up. I don't mind changing parts, but I hate shotgun troubleshooting. '93 Explorer A/T, A/C, 4x4. Thanks

 

[Ira]

Got a question for you. When you turn the key over to the RUN position, (not START), can you hear the fuel pump running for about 3 seconds? If so, your fuel pump relay is probably good. If you don't hear it, it could be either the relay or the pump itself. If the truck does actually start, I would say your pump is working as well as the relay.

How long do you have to crank the engine before it starts? If it takes more than 3 or 4 seconds to start, it could be another problem. It could be a faulty check valve in the fuel pump. The check valve is designed to keep the fuel system pressurized when the engine is turned off. This will make the engine easier to start by not having to build up fuel pressure when it is restarted. If the check valve is bad, it will let fuel drain back thru the fuel system and go back into the tank. If this happens, it will take a short time of cranking the engine before the fuel is picked up and gets to the injectors.

Does the engine start right back if it is shut off and then restarted within a couple of seconds? If so, I would think it is the fuel pump check valve which means the fuel pump would have to be replaced. Something you can try to verify this, after it has sat for a while without being started, turn the key to run and allow the pump to run until it stops (about 3-4 seconds). When the pump stops, turn the key off and then back to run for a few seconds. Continue doing this several times without actually cranking the engine. After going thru this process for about 30 seconds, try starting the engine. If it starts right up, replace the fuel pump because the check valve is bad.

BTW, most people here on the site think of the FPR as the fuel pressure regulator instead of the fuel pump relay. I know it can get confusing. The fuel pressure regulator usually gives problems while the engine is running. These problems usually start with a check engine light after running 10-15 minutes. When it is defective, you will usually experience rough idleing, poor engine performance, as well as lowered fuel economy. This can occur all the time or just intermittently as mine did. Believe me, I still remember the headaches.

[Edited by Ira on 11-14-2000 at 04:04 PM]

 

[SnowLover]

Thanks, I had my lovely wife try your procedure this morning. She reports that the fuel pump (or something) did run after she turned the key ON. I asked her to repeat that procedure a few times and she said the beast started right up.
SO......... I guess maybe I am looking at a bad fuel pump check valve. Next Q is- how hard is it to change? Is it integral with the pump (which is no doubt in the tank)?
Or would I be lucky enough to find the check valve in an easier location? I sure appreciate the tech help. Thanks again.



If it has t*ts, wheels, or wings, sooner or later it'll give you problems.

 

[riffman]

don't mind me...i just want e-mail updates...mines doing it too.....thanx!

 

[flyguy]

What you need to do is get a cuttin torch... and crack that fuel tank open...get a better look... oh wait... nevermind.

 

[Ira]

The torch deal would be interesting, but you would get a BANG out of it...sorry but I had to. Reminds me of a fuel tank I was working on one time. The vent in the tank was too small so I decided to increase the size. I removed the fuel tank and drained as much fuel as I could. I then proceeded to fill the tank with water (and let it overflow to flush out the excess gas that would not drain) so it would not explode when I drilled a larger hole in it. I drilled the hole and then soldered a piece of copper tubing into the tank. When I was finished, I was plagued with trying to get the water out of the tank. I turned it over, shook it, and did everything I could to get it out, but there was still approx. 1/2 gallon or so left. I decided to drill a 1/8" hole in the corner of the tank to allow it to drain. This worked fine and I got all the water out. I then proceeded to solder the hole up. As soon as I got the torch near the tank, BANG. The tank had been on the ground and when the fumes ignited, the tank went about 2 feet over my head. I had to change underwear because it scared me so much. The tank landed and was ballooned out so I had to replace it. I thought the water would have neutralized the vapors, and it did while the tank was full of water, but as soon as it was drained, it was explosive again. Moral of the story...don't try to solder anything that has fuel vapors left in it. The only way I have heard of being able to do this is by running exhaust from an engine by way of large hose into the tank while you are soldering or welding.

Now for your question. The check valve is an internal part of the fuel pump so the complete pump has to be replaced. Sorry for the bad news. In order to do this, you have to lower the tank, so run the fuel as low as possible first. I have not had to replace mine yet, but the previous owner of it did. He told me that if I ever needed to replace it, simply roll the carpet up in the back and remove the screws. He had actually cut a hole in the floor after completing the pump replacement and put a piece of sheet metal back over the hole and ran screws down to hold it in place. I never knew he did this, but he said now the pump could be replaced in less than 30 minutes WITHOUT having to drop the tank.

Hope this has helped you. Just watch those fuel tanks. They are like gigantic mexican jumping beans when exposed to flames.

 

[riffman]

soldering IRON...IRON....slower but safer.....gotsta get really hot though....

 

[SnowLover]

Thanks to all! It will have to wait until I have the motivation (or the truck quits running). I am an aircraft
mechanic and I HATE working on cars, but I guess it beats the auto repair shop in town that charges $65/hr. Suddenly
the damned thing is running and starting much better! And
I am not nearly brave enough to try any fireworks near the tank. Interesting story though..........

 

[roadkill]

FYI:

Ever since I had my '92 explorer, I never get a quick start if I turn the key and crank it over right away, doesn't fire right off. But I always turn the key on, let the pump pressurize till it stops, then crank it over. Hot or cold. Works every time for me! If it's the check valve, well, it's a big task to fix just to save 3 seconds at the start.

Good luck!

 

[Ira]

I too do not get instant starts. Sometimes it takes as much as 5 seconds, but from what I understand, it is taking much longer (10+ seconds) for his to start. The 2-5 seconds is pretty much typical, from what I understand.

 

[flyguy]

Well.. i get instant starts! I didnt untill I got my Optima battery though... wasnt even fuel related I guess. Man... i didnt realize someone ACTUALLY took a torch to a gas tank... sometimes I wonder about you guys... next thing ya know someones gunna get herculiner all over there hootus...

nick

 

[Chris Jella']

Roadkill, Ditto on your start method. Mine starts everytime if I start it that way. If you just cram the key in and turn, sometimes it will sometimes not. I wondered if there was something wrong or was just the nature of the beast. CJ

 

[wilk1]

Don't know if this is true, but an engineer made an assumption that the extra cranking was a design to bring oil into larger engines before starting.