troubleshooting fuel problem

[hertfordnc]

It's raining hard here and the truck is parked over huge puddle. Normally I would be out there trying a bunch of things but it's pretty miserable so I'm hoping to get some smart suggestions so i can be ready when I get a break in the weather.

Truck died and would not restart, thinking fuel pump.


Truck was running great but I had a CEL, first the code said it was running lean. I addressed some worn hoses (vacuum leak) Then the CEL came back on and the code said it was too rich. But it was still running great.

It stalled at a light and would not restart.

I poured some gas down its throat and it fired right up.

I hot wired the fuel pump at the inertia switch and it did not fire up.

Towed it home and changed the fuel pump. It starts but it won't stay running, like it seems to getting some fuel but not enough to run right.

I have not checked the fuel filter but it was fine a few months ago when i was troubleshooting a different problem.

thanks

Dave

 

[stamp11127]

What is the fuel pressure at:
Key off
Key in run for the first few seconds
While running until it dies

 

[hertfordnc]

I don't have a fuel pressure gauge but here's what I got so far;

changed pump and filter. Filter was definitely constricted but it made no difference in the problem

The truck will start, struggle to find idle, run for a few seconds then die.

Someone suggested clogged cat but can it go from running hard to not running at all so quickly? Last week i towed 3 tons at freeway speeds for 200 miles with no problems.

Water in fuel? Maybe, I had burned though 3/4 tank when this began

I have NO CODES.

I am desperate, We are a family of four and this is the only car that we all fit in (other vehicle is a 91 F150)

 

[stamp11127]

Without any additional info on the various systems used to keep the engine running, you have a long list of "could be's" to deal with.

Similar to going to a doctor who doesn't take your vitals but only interviews you. What do you think is wrong with you? How well do you think that would work? Nothing like rolling the dice with your life.

Check with the local auto part stores for a loaner, buy fuel pressure gauge or take it to someone who has the tools to diagnose it.

Describe the idle in more detail please.

 

[hertfordnc]

The frustrating thing is that i don't think it's long list of could be's if i could just connect with some expertise.

I think someone who really understand this system could match my symptoms to a failed component.

It starts quickly and idles smooth for about four seconds. I've ruled out the MAF and the Idle controller.

A new fuel pump and filter should rule out a pressure problem, right?

Then what?

I even gave my credit card number to "just ask .com" a guy who said he was an expert responded, asked if it ran with MAF unplugged, I said yes and I never heard from him again.

So, what is the next likely component that would cause this?

Throttle position sensor?

 

[stamp11127]

Well lets see, it takes four things for an engine to run...
1) Air
2) Fuel
3) Spark
4) Compression

Since we are not in a vacuum that leaves the last 3. When one of them is removed it will stop running.
Rule each one out, when you get to the one you can't, that may be the problem.

Let us know what the problem is once it is corrected.

 

[Bedrck47]

I think someone who really understand this system could match my symptoms to a failed component. QUOTE]


Until you take the time to post your fuel pressure readings you are spiting in the wind.
You do have someone that understands the fuel system trying to help you. But it appears to me that his request for information isn't what you want to hear.

You ask "A new fuel pump and filter should rule out a pressure problem, right?" How do you know unless you check those fuel pressure readings.

 

[stamp11127]

One of the steps in diagnosing problems is to get relevant data. Since you have replaced the pump and strainer you would think that the combination is within spec. Is it?

By checking fuel pressure while running and after it has stopped you will establish if the pump is within spec or possibly cutting off from an electrical problem. Should the engine die and the fuel pressure is within spec, then the fuel system is removed from the problem. A clogged fuel filter will show up as a low pressure reading.

As stated earlier, let us know what you find.

 

[hertfordnc]

Don't you hate it when someone posts a question, gets all kinds of help from the group and then doesn't come back to tell what happened?

In my research i found lots of threads like this going back several years but none had useful conclusions.

I had fuel at the rail but not enough.

I changed the fuel filter and it was pretty blocked up but it did not solve the problem.

I took a cheap bug sprayer filled with gasoline and put it to the fuel line aft of the filter and the truck fired right up. This is a great trick. About half the time the gas will melt the seals in the sprayer so it may be a one-time use, but it puts out about 45 psi and rules out a lot of trouble.

Sow then i knew it was in the tank. My first thought was that I got a bad pump (it was really cheap) so i went back and got a Bosch.

Still didn't work. THat led us to look at bad grounds because 80% of electrical problems on older cars are caused by bad grounds (Dave's rule)

SO i fount hte ground and put it directly to a cleaned surface - still didn't work.

But I knew the problem was in the tank so finally I pulled the tank all the way out and found the hose going from the pump to the pump housing had a crack.

This never occurred to me because I had changed the pump and hose just six months ago.

But I don't remember the last time i changed the filter and it being clogged created the back-pressure that shortened the life of the hose.

I cheated and tried to change the pump without dropping the tank. THere's enough room in there with spare tire out of the way you can just drop a couple bolts and lower the tank without disconnecting everything. But in this case, the lack of visibility led to missing the damage to the hose.

So, to some future backyard mechanic who finds this thread via google some time way in the future, I hope you found this mea culpa helpful. I also hope Bernie Sanders is president.

 

[Bedrck47]

Just how dumb are you??????

Read what you posted

"I had fuel at the rail but not enough."

Someone suggested you check fuel pressure But you didn't

Then you say that you "took a cheap bug sprayer filled with gasoline and put it to the fuel line aft of the filter and the truck fired right up".

That would prove it wasn't a electrical or ground problem.

Had you simply check the fuel pressure in the beginning it may have saved you doing all kinds of things that wasn't needed.

You turned to the forum for help and advice but you wasted yours and everyone's time and effort by not listening

But what I truly loved about this thread was your comment
"I think someone who really understand this system could match my symptoms to a failed component."

And again you were given good sound advice to check fuel pressure Had you done that the results would have pointed you in the direction of checking the fuel system from the pump to the injectors and you most likely would have found the leaky hose. I am surprised that you couldn't smell fuel leaking but that could be possible because you had your head where the sun doesn't shine and therefore you nose was blocked

Maybe next time you will follow the good advice that was given to you.