question about possible fuel issue with this truck.

I am able to drive the truck about thirty minutes, but after that time it no longer wants to run; acting like it can not get enough fuel (on an uphill slope.)

I was able to short term clear the problem by knocking the truck out of gear (manual) and reving the engine. The The truck has dual tanks that acted up when my dad was still alive. It would pump fule from the back tank to the front tank; one time even over flowing the front tank, which my dad did not use.

I am thinking I could replace the frame mounted fuel pump and that should help, but I was wondering if anyone may have another suggestions.

By the way new member and a lover of ford products.

I own a 96 T-bird and loved to death a little 88 Mustang LX.
I am also going to buy the F-150.

 

welcome to FTE!

My 88 F150 has the same problem with pumping the gas from the rear tank to the front and overflowing the front tank if your not careful. There is a selector valve that just needs to be replaced. I still have to take mine off and see if i can just fix it or if it needs a whole unit.

The part about reving your engine to fix the problem doesnt make sense for a fuel starvation problem. Like if you arent getting enough gas reving it should make it worse. Most of these trucks have a filter on that tank selector valve. Do both tanks do it or is it just one? What engine/year/wheel drive truck do you have? I'm wondering if it isnt flooding itself or something. How is gas mileage?

 

Sounds like something is wrong once the engine warms up and the computer starts running off of the O2 sensor.

When you first start up, your computer runs your engine on a predetermined fuel-air ratio until the engine warms up.. Then, it takes information from all the sensors to determine the new as-it-goes fuel-ait ratio. The easiest way to find out is to ask the computer (pull codes)....It's a lot easier than it sounds, and I've found it to become invaluable.

I wouldnt think that it would be your high pressure pump, because it works for that first 30 minutes.

 

The truck is an 88 F-150, two wheel drive with the 4.9L straight six.
The fuel milage is actaully pretty good. It is estimating between 14 and 17 per gallon (usually).

The problem presented itself after running out of fule in the front tank one dy and has been doing it since. I have not tried it running on that tank (the front one) since because of the redirection problem and I was afraid that it might have cloged the pump. I initally reved the motor because I thought it was a cloged filter and I was trying to keep the motor running. It may not have corrected the problem but it did clear up for a while.

It just seems odd that I can drive it twenty five miles before it starts to act up. It seems like when I have to slow down from highway speeds to city or side road speeds is when it shows up worse.

The truck actually does not idle well until it warms up a little. When it is first cranked it will idle for about thirty seconds and then just slowly stall out. after it was driven about three or four blocks, it would then idle fine. I think a code reader would be a good investment. I just did not know if it would code on a problem like this. Thanks.

The truck does need a lot of work on the following items before I would drive it to far.
A/C, Many gauges don't work or work improperly, Minor suspension work including shocks and struts, and sand, prime and paint.
But this truck is a good one. It was my dads and I feel about this truck like I do about the house where I grew up. It is important and means something to me.

I appreciate your help and suggestion.

Don Malone

 

Yeah, i have the same truck but 4x4. Does yours have the granny gear tranny? It almost sounds like a fuel clogging problem. First, do you know where your fuel pressure regulator is on your truck? You should check that out. I had alot of problems with mine until i realized it was leaking. Its not fun to get to, its under the intake manifold.

I doubt its your o2 sensor, if it is that bad to the point it would cause the symptoms your having, it would throw a check engine light, and the computer doesnt always run off of the o2 sensors, even when its warm. I would recommend pulling codes, you can get a walmart scanner for 20 bucks, or have it done for free at a parts store. Just remember, if you have a code coming up "o2 lean" dont go out and just replace your sensor, a lean code could be caused by many other bad components.

 

I see it in the manual, and it do look like a pain in the .....
It also makes sense that that could be the problem. Thanks for the tip. I thought it did not seem right that a fuel pump would act like that.

I am going to follow your advice and get a code checker. It may not help in this instance as I am leaning towards a trip to the shop. I don't have a garage to work on the truck in doors.
I am willing to try alot of repairs but when it comes to removal of the manifold and throttle body. I may just pass on this job. As I may be in over my head there.

Thanks for all of your help.

Don.

 

I didnt mean that the O2 sensor was bad, I was just meaning that it sounds like something is going wrong once the PCM switches over to the closed-loop system, dont know how that would be FPR, since it seems that if it was the FPR, he would have trouble all the time, not just after it warms up, right?

Might it be something along the lines of a plugged fuel filter? Even then, I dont know how it would only show up after the first twenty or so miles

 

I was thinking along the lines of his truck is cold when he first starts it, then when he drives it for a while it warms up and it doesnt handle the extra gas very well and loads up. But now that you menchan it, I think it may be some sticky injectors or something. These trucks do have injector cooling fans so i wonder if he's having a problem with his injectors getting too hot and starting to stick, or something like that. A leaky FPR will usually give you bad gas mileage too.

 

There was one thing I did not mention (and I apologize for forgetting. When it gets hot it does not want to crank (it seems). turns over good but does not start. The running problem has has for the most part, been seen only on mild to severe grade climbs. Not noticed on down hill grades.

 

Also the first thing I did was change the fuel filter. I figured if it was trash sucked into the line, that it may have helped at least a little.


I would have edited the above post from last night, but it was already locked.

I appreciate the feed back and help.
Don

 

Yeah, you can actually see your FPR under the intake manifold and all you have to do is pull the vacuum line off of it and then start your truck and look for gas coming out, or if your vacuum line is all hard then you know it has soaked up a bunch of gas. It sounds exactly like the problem i was having. When the truck was warm it couldnt handle the extra gas from the leaky FPR and wouldnt start until i held my foot down to the floor and then it would start to catch and fire and then finally once it cleaned all the gas out it was fine. But you can actually replace the FPR without removing the intake manifold or anything. You just need some socket extensions and a knuckle joint. I did mine in my apt complex parking lot in the dark.

 

Thanks. I'll check that out.

 

Try this next time it's warm, and hard to start. Push and hold the throttle to the floor. At WOT, the ECU will actually shut off the injectors during start. IF it cranks, it should do so on whatever fuel is sitting in the intake. My guess is, on a warm engine that cools down, that fuel is evaporating, thus making the engine start better when it's cold. Immediately trying to restart it when warm, it still has unspent fuel in the intake, thus the flooding condition. Does it smoke a little (black) when you do crank it hot? If so, extra fuel is getting in there somehow. Either a failed FPR or failed injector. Something's sticking open. Revving the engine works, because you're opening the throttle plates and giving it enough air to burn excess fuel. Your good (not great) mileage is contradictory of the symptoms, though. Normally, if the FPR fails, that will gulp down a whole brontosaurus in short order. But if an injector is sticking, it may not.

Oh yeah, try the WOT cranking test when it's cold too. If it cranks cold, you got fuel going in when it shouldn't be. Obviously, if it cranks, take your foot off the throttle quick before you wind up sticking a rod through the oil pan.

 

I have not noticed a smoking problem and I have to admit that the problem is recent enough that I don't have a positive knowledge that the mileage has not dropped off.

Just how warm ( how long to idle or drive) does it have to be for the crank test to be correectly done on the warm engine?

The truck has much that needs reworked or replaced. One of these items happens to be something with the fuel gauge. neither tanks reports the correct levle of fuel. We pretty much make notes when the truck was gassed and note both the milage and the gallons pumped. I use 15 mpg as my baseline and one day when I went to fill it up, the pump stopped way sooner than I expected.

Thanks for the help.
Don.