Working on a 1987 Ford F150 4x4 (4.9l) truck was sitting for five years. Replaced rear gas tank, fuel pump in gas tank, fuel pump on rail, fuel filer, new injectors. Eliminated front gas tank. Have fuel pressure of 50-60 lbs. Truck will start and run for a minute then it acts like its running out of fuel and shuts off. Any suggestions on what to try next. thanks

 

Why start a third thread for the same issue?

https://www.ford-trucks.com/forums/1...sperately.html

https://www.ford-trucks.com/forums/1...-f150-4x4.html


It's perfectly acceptable to "bump" an existing thread if there have been no replies in the last day or two.

 

RLA has a nicer reply. This seems fitting too though.
https://www.ford-trucks.com/forums/1491270-i-didnt-like-the-answers-from-my-last-thread-so-im-starting-a-new-one.html

 

Sorry, I apologize. New at this. thanks

 

No worries. Hope that didn't come off too mean spirited, that wasn't the intent. Best of luck with the repair.

 

You "eliminated" the front tank. Before you said you had done that, you said you put a new fuel pump on the rail, so I am operating under the indication this was a pump for a dual tank setup.

So...

What did you do with the ports for the front tank (top ports on rear of rail pump)? Are you introducing air into your fuel lines?

Sometimes trouble shooting a computer starts at the outlet. So not meaning to sound dumb or make you sound dumb, is your tank selector switch set for the rear tank? Is it wired correctly? Is it bad?

More technical information for others to use.... When it idles as you squirt fuel in the throttle body, what RPM is it idling at? Does it idle smooth and even? Rough? Fluxuating RPM?

Do any gauges in your cluster work or is the whole thing dead? Have you checked fuses? Pulled your instrument panel out and made sure wiring is attached? If just the fuel gauge isn't working but other gauges do, is it pegged way past full or way past empty?

[Some of the following is moot if you have fuel spraying through your injectors, but... something is amiss.]

Does the pump run 1 second at startup?

You replaced in-tank pumps, so I will guess you properly attached the wiring harnesses. Have you checked for current on the wires to the pumps?

Maybe some of that you've answered in one of the sundry threads. Not all of that would help *me* answer jack squat (some of it would, though). But that would be the stuff I would check/double check and info I would provide for the guys who know about this issue.

Just....

Do it in this thread.

 

X2...no worries. The link to another thread about starting new posts is not what this forum is about. It started as a tongue in cheek alcohol induced spoof that grew to epic proportions.

Personally I think a moderator should remove it. It's not technical based and degrades the wealth of information that other members provide.

We are here to help and guide you.

 

I completely disagree. While I did gently scold the OP, I did provide some web etiquette to follow.

I also provided links to their previous threads for those who may want to look at previous dialog.

This was also done so the OP could find them.

 

Can't argue with patience. Once in a while I get a little out of line. RLA, thanks for being a voice of reason and as always, helpful.

My apologies to the original poster. My initial post was troll-ish and not helpful.

 

Responding to one bolt short, completely eliminated the front tank, run new line from back tank to fuel pump on rail left original like from there on up. Disconnected return line from front tank and run return line to back tank. No lines are connected to the front tank. Gas gauge working properly and so are all the other gauges. Turn key off and on 5 times truck will start up and run for a minute then I start spraying gas into throttle body and the truck will run smooth idles at 1000 rpm will run on day if keep spraying gas in throttle body. When I first started working on it gauges did not work but I found blown fuse and replaced it, now they are all working. I would guess when you turn the key on and the pump runs for a few seconds the injectors are getting fuel. I replaced injectors yesterday they are brand new. I have double and triple checked everything I knew. Would like to get this truck running for it is a very nice truck. If I can't solve the problem will have to tear apart and I don't want to do that. Thank you for all your help in trying to located the problem.

 

I reviewed the old threads. What is your fuel pressure? In one thread its 30psi, and another is 50psi. This thread says 50 to 60. A 4.9L uses pretty high pressure. How was this tested?

 

I was under the impression a 4.9L had LOWER fuel pressure where 50-60 psi was top of that range.

*My* 4.9 using just the dash teach reading (so take this for what it's worth and anecdotally at best) idles a bit lower 800-900 RPM. On start it will lug down to 600 a couple times, self-correct and *spike* at 1000, then settle in.

Now, this is where I sit down under the shade tree, crack open a beer, stare at the truck and go into a trance to become one with the engine.... [Okay, okay, technically it is a "nap".]

Fuel delivery seems fine to the injectors. It would almost seem to be flooding, but can not be the case since *additional* fuel in the air intake makes it run.

Fuel and air introduced into the combustion chambers separately = no run. Introduced concurrently = run. That screams timing issue to me.

It could be electrical (distributor a few teeth off) or mechanical, which I haven't torn into a 4.9 to have a mental picture of what it looks like or to know if the cam can be positioned wrong. Worn cam? Wrong or broken lifters?

Was a new distributor installed at some point? If so, was it installed on the *compression* stroke of the #1 cylinder?

I'm not saying tear into your valve train. I'm brainstorming, "Where does this rabbit hole *possibly* lead?"

That's how my brain works through the info you have supplied.

Good luck.

 

I agree with the above.

I will also add does the fuel pressure drop off when the engine starts to die?

If the fuel pressure remains in the 45-50 PSI range at idle and the engine still dies then you are looking at the injector power or trigger pulse dropping out.

Since the truck will run with gas sprayed into the intake you have spark.

 

This is like watching a train wreck. Fascinating how so much destruction unfolds.

The only thing consistent here is inconsistency. One thread, the truck will not run except on a shot of fuel into the intake, next time it runs for a minute? Now suddenly, we have the rear tank deleted. Measured fuel pressures range from 30 to 50 lb with no explanation of the method used. My advice in the previous thread went unanswered and with the tank delete I am becoming increasingly suspicious that the return line was capped. Any feedback from the OP has been difficult to obtain at best.

Think I may just go find a bottle of Jim Bean and go join 89F2urd!
​​​

 

Thanks for quick reply. I'm assuming the distributor has not been changed. When truck is running by spraying gas in throttle body it runs very smooth no popping you could put a glass of water on motor that's how smooth it will run. I thought if it was out of time it would be hard cranking and not running smooth. When first got it started, lifters tapped a little but now is quiet as can be.