So, 91 ranger 4.0l engine, it's my first truck and I've used it for work for awhile. Last year it started having fuel issues. I changed the fuel filter and ut ran fine for awhile,but it had not impressive pressure coming from the pump I noticed. I figured that the pump was weak but it ran fine for about a month and died again. The pump was dead.
So I pulled the bed off and put in a new fuel pump and it started up. Ran like crap for awhile while the computer was running and while it smoothed out sone it didn't go back to running well. At the time I blamed older gas since it was a year before I got to fixing it. Lucas made it run better but still not great so my conclusion was old gas.
Bolted the bed back on and....it coughed once a died. I figured maybe I kinked a line so unbolted the bed and pulled it back to see and it was fine. I have good pressure past the filter.
I replaced the fuel pressure regulator afterwards to see if it was that. No changes. The fuel rail appears to have pressure but without a gauge I don't know how much but tripping it with a screwdriver gives me a little more than a dribble, definitely not the 50psi Im expecting.
Car starts on ether so it's definitely fuel. I've checked the vaccum line from the fuel pressure regulator and it's fine. It even has a newish IAC.
Am I missing something stupid? I'm pretty much at replacing the fuel line from filter to fuel rail but it's gonna be a bitch and I'd think if the line was damaged in some way, it would leak and I have no leaks anywhere.
I feel like I'm missing something very stupid, thoughts?
What do you mean by tripping it with a screwdriver?
Return or returnless system?
In reply to wvumtnbkr :
Pushing in the pin on the Schrader valve on the rail.
It's a return system
At this point, have you gone through the electrical? Like make sure the grounds are really sound, and the source is full 12V?
Also, with the fuel pump running, is there fuel coming back through the return line?
And I forgot that those vintages had the collision switch in it- that could be causing a voltage drop, too. Have no idea where it would be on a ranger.
I haven't checked for a full 12v, my assumption is the electric side( at least to the pump) is fine because of pressure being great from the pump. I can definitely check.
Doesn't the inertia switch cut off the fuel pump? I can reset it to make sure though.
I didn't check the return line, good idea.
Not the inertia switch, I whacked it and reset it just in case but no go
If you still have the bed off can you disconnect the line at the tank and rail and spray compressed air through the line? How much rust was in the tank? I used to have a 91 Ranger and rust was the downfall of that truck. I wouldn't be surprised if you've got some junk in the rail or fuel line.
You need to pull trouble codes, could be a bad temp sender.
Will it run on spray cleaner?
Patientzero said:
If you still have the bed off can you disconnect the line at the tank and rail and spray compressed air through the line? How much rust was in the tank? I used to have a 91 Ranger and rust was the downfall of that truck. I wouldn't be surprised if you've got some junk in the rail or fuel line.
Mine has a plastic tank so there was zero rust. Nothing at all in the tank either.
Blowing the lines out isn't a bad idea at all either
bentwrench said:
You need to pull trouble codes, could be a bad temp sender.
Will it run on spray cleaner?
I don't have a check engine light on but I could buy an obd1 scanner and see.
It will run on starting fluid.
In reply to Antihero (Forum Supporter) :
You don't need a scanner to do that- a paper clip shorted across the right lines will make the light flash. And I am not sure if there's even a code for that. the tests back then were pretty darned simple.
Along with the above suggestion about the hard lines getting clogged up- are there any kinks in the line from impact? If all the soft lines, pump, regulator, etc are all new, then the last thing is the hard line.
alfadriver said:
In reply to Antihero (Forum Supporter) :
You don't need a scanner to do that- a paper clip shorted across the right lines will make the light flash. And I am not sure if there's even a code for that. the tests back then were pretty darned simple.
Along with the above suggestion about the hard lines getting clogged up- are there any kinks in the line from impact? If all the soft lines, pump, regulator, etc are all new, then the last thing is the hard line.
Oh yeah, I know but a scanner is cheap and easier than the whole counting the blinks thing.
I didn't see any but the hard lines are basically only in one spot that's a bitch to see and wrapped around the frame, good point though
Instead of buying a scanner, buy a fuel pressure gauge. I have fooled myself on occasion with the simple Schrader test, and chased my tail only to find out some wasn't enough once I finally put a gauge on it.
What brand is the replacement pump?
gumby said:
Instead of buying a scanner, buy a fuel pressure gauge. I have fooled myself on occasion with the simple Schrader test, and chased my tail only to find out some wasn't enough once I finally put a gauge on it.
What brand is the replacement pump?
Not a bad idea, my plan was both but really the scanner is probably less important
I believe it's a Delphi but I'm not sure
These things have a known issue with the intake gasket. You may want to smoke test it. Also a vacuum gage on it may tell you something. If the intake is leaking bad enough the afm is not seeing air flow so no fuel.
first chk the fuel pressure as others have suggested.
Sounds like you have strong pressure at the tank but none at the rails.
so there is an issue between those two points, yes?
jfryjfry said:
Sounds like you have strong pressure at the tank but none at the rails.
so there is an issue between those two points, yes?
I'm assuming that without a gauge since after the fuel filter we have " fire hose" and at the Schrader valve on the rail we have " sad pathetic trickle) but everyone is right, I need to get an actual gauge on it.
dean1484 said:
These things have a known issue with the intake gasket. You may want to smoke test it. Also a vacuum gage on it may tell you something. If the intake is leaking bad enough the afm is not seeing air flow so no fuel.
first chk the fuel pressure as others have suggested.
That's a great idea, I had to replace the intake gasket very long ago but didn't even think of that.
I'll check vaccum tomorrow
Another thing to check on those is the pressure regulator. Pull the vacuum hose off and check for liquid fuel or strong fuel smell. They like to get a crack in the rubber diaphragm and bypass fuel.
In reply to Curtis73 (Forum Supporter) :
No fuel in the vaccum line but liquid fuel in the return hose. After I replaced the regulator and bolted it in there was enough pressure in the rail to slowly push fuel up thru the regulator too.
