Need help diagnosing 5.8 351w hesitation
 

I have a 1995 F350 crew cab 2wd with the 351w. The truck does fine for 30 or 45 minutes but as soon as you try to get the trans to drop into passing gear to climb a hill, it hesitates like it's running out of gas. You can keep it under 50 and not drop gears and it'll run all day it seems. I've tried checking the fuel pressure but my gauge reads zero, which can't be right. I tried another gauge and still get zero so I'm not sure if I have 2 broken gauges or what. I push the valve in on the test port and it shoots fuel up. It has a new ICM, distributor, fuel pump, filter, coil, TPS, and a new cat converter. I'm at a loss with it. My job depends on this truck and I really need a little help. Thanks in advance

Does it have any codes, stored or active?

What is the base timing set to, and does it advance when the SPOUT is plugged back in?

Any vacuum leaks?

That's unfortunate you're having issues checking fuel pressure. Do these gauges work on other vehicles? If so, I'd check out the valve on your rail. This spec is an important one to verify, so it's worth figuring out, in my opinion.

Did this issue come on suddenly or slowly?

I'm not sure about the timing. I have no way to check it, and it hasn't been messed with since I've had it for 4 years now. Every time I hook the scanner up it gives me a 111 or pass. What is the SPOUT and how do I check it? I just pulled the fuel pump back out to double check the wires, it's fine. It's a Dual tank system, and the front tank does not work.

It's so odd to me that it runs fine forever, but when you need to drop gears it sputters and almost dies. You can stop for a second and it's like it comes back to life (as in the idle goes back to normal) and you can take off just fine. Until you try to drop gears again. The trans fluid is a little low. I'm adding it now.

When was the last time the spark plugs, wires, distributor cap, rotor, and air filter were replaced? Basic maintenance is square one.

In trouble shooting an issue like this, fuel pressure is a critical spec to know. You need to figure this out. Can you check your gauge(s) on another vehicle? Having fuel come out of the shraeder valve is not in any way a substitute for verifying fuel pressure.

What color ICM did you install? An infamous mistake is installing the wrong one; the parts stores often don't get it right. There's a gray one, and a black one. A 1995 should have a black module in it. https://www.ford-trucks.com/forums/1...black-icm.html Black ICM vs Grey? p1351 - Ford Bronco Forum

How did you replace the distributor if you don't have a way to check & set ignition timing?

The SPOUT connector/jumper, when installed, enables the PCM (engine & transmission management computer) to control the ignition timing advance. To see base timing, you remove the jumper to prevent PCM timing manipulation, then see if the base ignition timing is at 10 degrees BTDC (truck warmed up, at idle). You will want to rent/barrow a timing light from an auto parts store, or buy one, to check the timing and then ensure it advances with SPOUT connected. I strongly suggest youtube for a tutorial on how to do it if you're not familiar; this video appears to give a good run down: Just be mindful of working around the spinning fan.

The spark plugs and wires were changed yesterday. The distributor was changed as a whole unit a few months ago and has been driven at least 10,000 miles since then. This is a delivery truck that drives a minimum of 250-300 miles a day. I was told with the electronic ignition that timing didnt need to be set. Air filter was changed maybe a month ago, there's no wetness to it, it looks brand new. The ICM i installed was a black BWD unit from O'Reilly's, as was the coil, distributor, and I believe the wires. We bought OEM plugs. The truck actually ran well after all that for several weeks. The cat converter was done a week ago when all this started.

I will test the timing, i just haven't thought to do that because of the way the problem came on. We hadn't done anything to the truck in about 2 months, and like I said that's about 10,000 miles for it. I definitely need to check the fuel gauge on another vehicle. I know fuel spraying out of the Schrader valve isn't a replacement for actually testing it, but when the truck is idling fine, and driving fine up to 45-50 mph, I assumed it was a safe bet that it has fuel pressure. I really need to get a gauge to work so I can watch the fuel pressure at 45-50 mph.

With the trans fluid being low, could that cause it to feel like it's running out of fuel when it tries to downshift to climb a hill?

Thank you for your replies

Okay, so the state of tune up parts is good.

I'm not sure on the trans fluid level; how much did it take to get in spec?

Fuel pressure under load is always best, but you have a point about it working up to 45mph. How does it do from a stop, in terms of acceleration? If you mat the pedal does it fall on its face at a lower speed? If low fuel pressure, it won't care if you're going 105mph or 13mph: if the engine is at high load for any time it needs fuel. If this problem is strictly speed dependent that is a clue.

What prompted the distributor change? The PIP is generally not new in a reman unit. Sometimes parts replacements like this can compound the issues and make diagnosis harder than it ought to be. Just something to keep in mind. "New" doesn't always mean in spec.

Hopefully someone smarter than either of us sees this and can help you get this sorted quickly. I'm by no means the resident expert.

^^^ What he said about the PIP. Rebuilt distributors come with unreliable PIPs. Not sure I trust the new ones made in china either. It is typical when the PIP fails that the truck runs better cold and worse hot.

When you replace, or even just move, the distributor you definitely have to set the timing. The weather is factor in timing. Old trucks with points would run good until it got cold and then wouldn't start until you set the timing.

I have seen several threads recently where people basically have to replace the whole ignition system. Sounds like you are almost there but I'm not encouraging you to throw parts at it.

You mentioned fuel pressure and fuel pump. That thought it not complete without considering the fuel pressure regulator.

Now I see you mentioned FPR in your other thread here:
https://www.ford-trucks.com/forums/1...ay-speeds.html

I think I'd proceed with timing, reading codes, clearing codes the right way, not by disconnecting the battery. Monitor codes, fuel pressure while missing and check or change that PIP.

Just because you change parts doesn't mean you can forget them. Parts swapping is not a substitute for diagnosis.

Read this first:

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

Yeah the FPR is brand new. I had no idea about the PIP. What gets me is we can let it idle in the driveway for 30 mins, then take off in it and drive it for 30-45 mins as long as I'm easy on it, but when I try to climb a hill and it needs to downshift it chokes. The last time we drove it, we got it up to temp in the driveway, then drove it about 25 mins to the store and went in for maybe 15 mins, drove it almost all the way home but it was trying to die every time it needed to downshift. We eventually had to pull over because it had no power up a hill and it sat for 10 seconds struggling to run, then just came back to life and I drove it home.

it does fine from a stop, it has power. That's why I keep asking about the transmission. As soon as I get to it today, should I just replace the PIP? the distributor I bought was a new BWD unit, not reman. I will check our the link you posted as well. Thank you for your help

You know, I don't feel comfortable saying the distributor was new. I know I told the guy I didn't want a reman, but he may have gave me one if that's all they had. I bought a lot of parts that day.

Try to test everything you can test. I wish more of us had better test equipment and documentation for these trucks.

There are tests for the PIP here in the forum and in the manuals. A fuel pressure gauge is not very expensive. Both are doable.

I can't say that your truck has only have one problem or which one it is. It's your time and your money. There are some VERY long threads here where people run in circles with problems like this.

I've hit a brick wall again and hope I can revive this thread. I set the timing, the check engine light is still on and I get a code 327 about the EGR valve. I've spent so much money on this truck now it's getting ridiculous, but here I am with a new EGR valve, new EVP sensor and a new PIP sensor. I hate to just throw all this at it. The truck ran fine again today for about 45 miles then started hesitating while climbing up hills on the interstate. We drove it home. I'm just not understanding how any parts could cause this. It was drove 20 minutes in to work, plenty of time to get hot, then drove the 45 miles up the interstate before it started again. I really thoiught we had it but I guess not. I'm getting desperate here.

having read through this i will throw my 2 cents worth in ...
i don't see where you have confirmed fuel pressure within spec.
it wouldn't be the first time that an electric fuel pump worked ok when cold but just couldnt keep up once it has been running (i.e. warmed up) for a while.

I did confirm the fuel pressure was 40 psi when I installed the fuel pump and filter about 6 weeks ago. I'll buy another gauge tomorrow and test it. Not too many options left honestly. I just assumed that the way we drive it for 30 mins to work, then 45 minutes up the interstate with plenty of hills meant it wasn't fuel related, but maybe the voltage is dropping for whatever reason after it's real warmed up. I did notice the upper radiator hose swelling at the radiator inlet, and I saw it drip a few drops of coolant on the cardboard I had laid down under it. It never gets hot though. Well, the idiot gauge never shows hot anyways. I know they're not a reliable gauge.

When I set the timing today, I may have turned it a tiny bit. Maybe. There is a slight miss at idle but you'd never know if you didn't watch the engine and see it as it's not nearly enough to feel in the truck. The only code was a continuous memory 327 EGR signal low voltage.

Could this EGR code cause problems only when it's very hot? I would think an EGR problem like that would effect it all the time.