eyancey

I have a 1991 E150 cargo van with the 4.9L 6 cylinder in it. Recently it developed a problem where it would start running rough at higher RPMs. It got so bad that I could only get it up to 15 or 20MPH...luckily I mostly drive it around on the farm so it wasn't a big deal, but I'd like to get the issue sorted out.

I tested the fuel pressure this morning. It was at 40PSI at idle, when I pressed the accelerator it dropped to almost nothing, and stalled out. Figuring it was the fuel pump, I replaced the pump in the tank, along with the fuel filter. After replacing the fuel pump, fuel pressure was much better, around 60PSI. While replacing the filter, I noticed what I think is a second fuel pump - I have not replaced it.

It runs a little better, maybe, but the same basic issue remains. It starts up fine, idles fine, but if I lightly press on the accelerator, it will rev up for probably 3-5 seconds, then starts to rev back down.

It feels like it's not getting enough fuel - like fuel is just spurting into the ejectors instead of being supplied a constant supply.

Any thoughts or suggestions would be greatly appreciated!

Thanks!

Eric

flareside_thunder

Pull the vacuum line off the fuel pressure regulator and see if that changes anything.

eyancey

Thanks for the response! I tried pulling the vacuum line off the fuel pressure regulator and it didn't seem to make a difference (I was sure to plug the vacuum line afterwards so as to not create a vacuum leak).

eyancey

I thought I would post a quick update. Today I was talking to a coworker and he mentioned the MAP sensor. During my lunch break I went out and started the van up, and while it was running I pulled the vacuum line for the MAP sensor from the vac tree (one advantage of having a van, I can reach the vac tree from the driver's seat).

Once I did that, I was able to rev it up with no hesitation. Of course it doesn't run well at idle with the vac line disconnected and ultimately cut off, but I think the MAP could be the issue.

In summary:
- everything connected: idles fine, dies when trying to accelerate
- disconnected fuel pressure regulator vacuum line - no effect
- disconnected EGR vacuum line - no effect
- disconnected MAP sensor vacuum - can rev up but doesn't run great

The thing is, I replaced the MAP module probably 3 or 4 years ago. I guess it's possible that it could be bad already, or maybe it's a wiring issue going to it? Any thoughts would be appreciated.

Thanks!

flareside_thunder

You need to pull codes. Just call me Sean did a technical sticky about how to pull codes that is at the top of this forum.

eyancey

Another update. I put some fuel injector cleaner in the tank about a week ago. I ran the van several times throughout the week to see if there was any effect, and of course there wasn't. I pulled the KOEO codes, only code that showed up was 558 - EGR Valve Regulator (EVR) solenoid – circuit failure.

Called up a guy I know that races Ford cars, he said he'd come over and take a look at. It had been two days since I ran the van last. Of course when he showed up I realized I left the ignition on after doing my KOEO test, and the batter was dead. Finally got it started, and wouldn't you know it, it ran great - couldn't get it to stall out at all. He noted that the idle was a little high and the timing sounded off, so he adjusted the timing.

However, while it will idle great and rev while in park, when driving it has no power (we didn't get a chance to do a road test while he was here) at all. Terrible miss and hesitation. I'm wondering if the injector cleaner is starting to work, or if there is something else going on. This weekend I'll try to do a KOER testing.

flareside_thunder

Your running the battery dead simply reset the computer therefore erasing all codes until it can relearn and test everything again. A friend of mines truck has been behaving similarly. Try disconnecting the spout connector and then driving it or free-revving it.

WildernessLVR

wrong thread....

ajbremer

Messages got a little off track there didn't they.

I removed the hose from the pcv valve and started it up and it ran rough but didn't stall - that seems like a possible good sign? I'll get a new PCV and let you know wazzz up.