Ok, here's my problem. I have an 88 F250 (fuel injected) which won't start. This is an intermittent problem, because it runs sometimes. I have good and constant spark and I know that fuel is being injected, because I can smell it under the hood and I can smell it out of the exhaust tips. After trouble shooting for two weeks, the only thing I can think of is that my Fuel Pressure Regulator is bad. If the diaphragm is broken, then the pressure behind the injectors would be too high and too much fuel would be injected. This is my only idea since it seems that the truck won't fire up because the mixture is too rich. Does anybody have any thoughts on this, or any ideas on how to test the regulator or remove it. I can't find a way to remove it, without removing the fuel rail, which would include removing the upper manifold. Please help!!!!!!!!!!!!!!!

 

Just test your fuel pressure...get a gauge..there is a valve on the fuel rail to put the gauge on and test the pressure. Should be about 39 psi.

 

Mustang, thanks for your help. I got two questions for you. 1. I don't have a proper gauge for the fitting, it looks like it's 3/8 inch, do you know the exact size or what kind of gauge or fitting that will work. 2. Does the engine need to be cranking while I'm reading the gauge. I'm assuming it does, simply because you need the fuel pump on to reach the proper pressure.

Thanks for your help

 

The key just has to be on, not cranking. So turn the key to the run position (you'll hear the fuel pump whine for a second as it pressurizes the system). I don't know what size the fitting is, but it's the same size as a tire valve, it's pretty generic.

 

mustang, I have some new information. I wasn't able to test for pressure, so I pulled the vacumn line off of the regulator and it was filled with gas. So I know that the regulator is bad, the diaphragm must be leaking or broken. My question for you and anybody else out there is how to replace this myself, or should I just take it in???? I've never done anything like this before, so I would need a step by step description of how to replace it. Thanks

 

well i just replaced mine on my truck... wut motor do u have? mines a 7.5 litre, all i did was pull the intake tubes from the throttle body off and the regulator was under them on the fuel rail.. drain the pressure with the vavle and take out the 2 little screws with alan keys im pretty sure.. and the one fuel line.. not sure if the regulator is gona be the problem.. but thats how to replace it.. parts not to much $ either... never solved my problem tho..

 

<!First of all, I gotta say that you probably shouldn't bite at the people who are trying to help you.......>
I just replaced one yesterday - been chasing a FI problem myself ('88 F-250, 351W/5.8L)-; I'm not sure of your skill level, so here goes:
You'll need a 4mm allen wrench (sure am glad I had a long one and a short one, and something to relieve the fuel pressure - I used a punch, and a short ladder. Remove the negative lead from the battery. Locate the shrader valve (bicycle tire looking thing) on the left fuel rail - inboard of the valve covers, valve was located towards the front of the engine - take the cap off, use the punch, fingernail, whatever, and gently puch down on the valve stem to relieve the fuel pressure. My regulator, and hopefully yours, is located on the left fuel rail towards the rear of the engine. Use the pictures and torque info - don't want to break or strip anything - in your booksRemember to disconnect and reconnect the vacuum line. The part number is on the valve - I took that number to Autozone - $19.00. The ladder was used to get my poor old aching knees up on the fwd crossmember.....
Hope this helps......Only took me about an hour, as I did NOT remove the fuel rail.

 

Montangrut, I just replaced the FPR on my '93 F-150 with a 5.0 and i did not have to take off my fuel rail, but i hope i never have to do that again, they could have put it in a better spot to where the cap screws were not upside down and in the back to get to them. Good luck on changing it out.

 

hey ducky, how did you depressureize and pressurize the system?

 

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ok, here's the new news. I took my pressure regulator off. (big pain in the butt) and put a new one in. That solved the problem of gas pressure, however, the truck still isn't starting. I rechecked for spark and I got good spark from the coil, and I also testing one of the wires and I had good spark. So I have no idea where to go now. I still smell gas out of the exhaust after I crank the engine, so I'm assuming that gas is going into the cylinder. I'm going to go change all my plugs and see if that helps, but if anybody has any ideas let me know

 

Take the cap off the distributor and watch the rotor while you crank the engine. Make sure it is turning when the engine cranks.

Also, Grab the rotor and try to turn it by hand. It should not turn.

I had this happen to me last week, the roll pin that attaches the distributor gear to the shaft broke on me.... At 1:00 in the morning on the freeway.

79 cent fix, but not easily obtainable at 1:00 AM on a Sunday

I feel you on the Pressure Regulator replacement.... I did mine a few months ago and it was NOT fun!

Good Luck

 

you know i have an 87 f-150, and i was having the same trouble some time ago, and the main reason, was that the timing was off and i needed a new fuel pump relay. So beofre you go and change everything, check your relay, and if you havent replaced it in a while, replace it.

 

oo one more thing is check all your wires, near your throttle body, because if any wires are rapped up and touching eachother, then it will overlap and confuse your computer.

 

The timming is fine. This is an intermittent problem. Nothing has ever been done to the distributor or timming chain. I still think that it is a fuel problem, but I will check the distributor and the rotor tomorrow. If anybody has any further advice, let me know please.