Fuel pump or FPR?

[JTH1972]

Okay everyone, I got a story...

A couple weeks ago, my 94 XLT starting acting a little funny. When cold, sometimes I find I needed to prime the key twice to get it to start decently. otherwise it wouldn't start with only one turn of the key. With acceleration, the vehicle seemed to be "surging" like I was pumping the gas in a rhythm. Overall acceleration wasn't bad and besides the revving sound in the motor, it wasn't jerky to drive, and fairly smooth when at a cruising speed.

Yesterday, it completely died on me at my inlaws place. Sat for a short bit, when to start the motor and it ran really rough, tried to give it gas and no response, still running rough and eventually died. F.I.L. and I played with a couple of things, he checked the rail for fuel, and thought it was air and gas coming out of the valve. When we went to check the motor again for the hell of it, it fired up no problem! Even the surging was gone with acceleration.

Today, same problem started to come up again. Ran fine for a couple hours this morning, then started acting up again. At it's worst, rough running and hesitant on acceleration after starting up, and rough idle. Eventually it went away and I had no problem on the highway. No CEL.

At home, I dug out the fuel pressure tester. After letting the engine sit for an hour or so to cool off. Turned the key once, and fuel pressure only went to around 10 pounds, second key turn got it up to around 20 pounds, started the motor (started fine) and the pressure bounced around from 24 pounds to 28 pounds, eventually settling at 28. With revving the motor, the pressure never went above 28 pounds. When I tuned the motor off, the pressure went up to 32 pounds.

I do have a replacement FPR on the way (needs it anyway) but anyone have any insight as to other possible causes or should I be looking at the fuel pump too? Does the Explorer have two fuel pumps on it like the Ranger?

 

[Anime]

It's very possible that it just needs a new FPR, or even that the pump is getting weak. If it's the original factory pump, usually replacing it is worthwhile, especially when the mileage gets pretty high.

Keep in mind there are other causes for low fuel pressure and hard starting though. You might have a fuel filter that is getting clogged up and restricting fuel flow, especially on some starts. Same as with the fuel pump, if the filter is factory original, it wouldn't be a surprise for it to be in need of replacement.

You may also want to check things like the spark plugs, plug wires, etc. since they might be causing the roughness, even if the starting is the FPR, pump, or otherwise fuel-related. If they have been in there a long long time and are wearing out, they could be the cause of an engine running rough all right.

The Explorer only has one pump, mounted in the fuel tank on the drivers side. You need to either drop the tank to get to the pump, or cut a hole in the floorboard above the pump to replace it that way.

You can buy bare pumps, or a whole new assembly. I suggest buying an assembly since it isn't that much more, and certain brands have stainless steel assemblies, which won't rust as bad as the factory steel one. Usually on Explorers that have seen winter climates, the stock pump is rusted pretty badly, sometime to the point it is rusting apart into the fuel tank, and you find a tank of rusty fuel with a rusty filter sock, letting you know the fuel filter is probably caked full of that rust as well.

Replacing the fuel pump, fuel filter, fuel pressure regulator, etc. can be a heck of an 'upgrade' - even though it just restores stock performance and lets you feel what you were missing.

 

[marragtop]

I agree with the fuel filter possibility. Replacing the fuel pump would be the last resort.

 

[JTH1972]

Fuel filter replaced about a month or more ago.

 

[RustySJohnson]

Three with similar problems?

I had issues with a rough idle when warm, it was just the little boot connecting the fuel pressure regulator vacuum line was squishy, soft, and lost vacuum. It was worse when warmed up and trying to restart. That little boot would expand heated up. There's another thread on here which is somewhat close to what you're describing and I had the same problem a couple weeks ago. http://www.explorerforum.com/forums/showthread.php?t=374394

The fuel pressure regulator is vacuum feed, if there's a problem with that, or a vacuum line anywhere you're fuel pressure will be erratic. Replace all of the connectors on the vacuum lines, they sell those by the pack and they're cheap.

 

[JTH1972]

I had issues with a rough idle when warm, it was just the little boot connecting the fuel pressure regulator vacuum line was squishy, soft, and lost vacuum.

The fuel pressure regulator is vacuum feed, if there's a problem with that, or a vacuum line anywhere you're fuel pressure will be erratic. Replace all of the connectors on the vacuum lines, they sell those by the pack and they're cheap.

The issue isn't really with a rough idle. It runs not bad from point A to B. Point C, D, and E isn't so good. Soft acceleration is rough, hard acceleration and higher RPM is smoother.

Considering the vehicle age, I'd be interested in changing the fittings. Where do you get them? Don't know if I've seen things like that here. Hate to try to replace all the vaccuum like with that hard plastic.

 

[JTH1972]

You may also want to check things like the spark plugs, plug wires, etc. since they might be causing the roughness, even if the starting is the FPR, pump, or otherwise fuel-related. If they have been in there a long long time and are wearing out, they could be the cause of an engine running rough all right.

Plugs and wires were replaced about 2-3 years ago.

 

[JTH1972]

The fuel pressure regulator is vacuum feed, if there's a problem with that, or a vacuum line anywhere you're fuel pressure will be erratic. Replace all of the connectors on the vacuum lines, they sell those by the pack and they're cheap.

Where do you get them from? I don't recall seeing them before.

So, replaced the fuel filter (again) as it turns out I accidentally had the wrong one on there (don't ask...). With no change in fuel pressure. Replaced the FPR (the bolt closest to the front of the engine is a PAIN to get back in place!) and again, no change in pressure. It is driving a little better (probably with proper flow from fuel filter) but pressure is still down and does repeatedly surge with acceleration, and noticeable up hill.

So, fuel pump may be next in line. Do I replace just the pump or am I further ahead to replace the whole unit? Who's done the job before and is it as much of a PITA as I think it's going to be?

 

[marragtop]

Are you sure you have a good gauge that you are checking the pressure with? Also, have looked for codes even thought the CEL may not be on? If you have to do the pump, I suggest doing the whole unit, not just the pump. You are correct, it is a pita. You either have to drop the tank or cut an access hole under the back seat. If you do a search, you may find detailed instructions on where to cut the access hole. I cant remember if it's on this site, or another forum.

 

[JTH1972]

I got a friend I can borrow another gauge off of, but irregardless, it's still not running right.

 

[jkalaskan]

Check your filler neck tube. Had similar problem, in addition to another not yet figured out. Three little bolts inside gas cap door, and two hose clamps at gas tank.
Filler neck tube rust out because they are exposed to spray, rocks, etc from the tire and when they get holes in them, it lets in water and dirt. If its not bad it will clog the fuel pump filter in the tank and with the action of the fuel sloshing back and forth will be clogged worse at some times than others. Changing out fuel pump is not that hard for a basic back yard mechanic. Did one on 96 and one on 99 in Costco canopy in backyard at 10 degrees. Did have a propane heater going to warm hands. 3-4 hrs. (Clean tank out good. Even consider taking it to car wash and pressure washing it out if it has lots of dirt. Of course dry in out good before putting back on.)

 

[nemoremo]

Fuel issues as well on a 94 Ex.

So I recently had some coolant leaking issues that seem to be resolved by replacing the lower intake manifold gasket.

http://www.explorerforum.com/forums/showthread.php?t=375355

After I got everything back together last night I test fired the Ex and it started right up. Two second crank. Ran fine for 10 + minutes. Enough to know the t-stat opened and it was heating up and no coolant leaking. Great.

Snowed 10 inches last night. Went to start the Ex. and not firing off. Tried to but no dice. Cranked for 8 or 10 seconds ( more than I have ever needed) and still no start.
Got out and the fuel smell hit me. Gas was literally dripping off the back of the engine.

Scared the piss out of me. Didn't have time to pull it apart this AM, but would love to hear anyone's thoughts on how it went from running great to gas running off the block.

My thoughts: no pressure to fuel rail, until I rehooked the battery and started almost instantly after that. No leak as long as the injector was relieving pressure into the cylinder ( or nothing I could detect).

After the fuel system was pressurized it leaked out during the night or this am when I tried to start.??????

I know I rehooked the tiny vacuum to the FPR ( on engine left front under the radiator hose area). And will check again. For what I don't know.

I didn't like the way the fuel rail went together and am not sure how I could have done it differently. The manual I have says install the injectors into the fuel rail and then push it together gently when installing to intake manifold. It didn't seem to want to push together 'gently'. I just went slow and kept twisting the injectors a bit to make sure they were lined up and didn't bind but not how i envisioned.

It didn't seem like the fuel supply line ( back of engine drivers side) was leaking but again, I didn't get it back apart this am.

Any idears? TIA.

Mods: if you feel this should be in a separate thread, do what you will. It sounded like a few on this one already have some familiarity with the fuel issues.