98 24V, Only 17PSI, Sometimes Hard Starts?
 

Finally got the gauges put in this afternoon, to see what Im working with.

History first:
98 24v 3500, 5spd, 3.54 gears 4wd
251k miles
Been stock all its life
New VP44, holley lift pump, and fuel gauge last January 07
addative put in every tank


The issues:
sometimes hard starts, only after sitting for a couple hours. If the engine is warm usually fires right up. the odd part to this, is the worst it did is not start, just pulled down batteries. Floored it, and started fine. Thinking APPS? Did check it, and adjusted it, seemed to make a small difference in driveability. Cleaned the IAT sensor as well, new air and fuel filters last week as well. Havent gotten to the crank position sensor yet to check it out.

Power:
Found this driving into a headwind across Kansas. Pulling 10' high hunk-o-equipment on a trailer, ~8-10k pounds. Could quite pull 5th gear. Hence the now added boost gauge!

Also, fuel mileage, pulling 75mph 5k pound trailer (open car hauler with car) CO to CA get 12-13mpg.


What I know currently:
What the gauges now tell me for the whopping 15 miles Ive driven them. EGT can get just over 1200 in high rpm, foot on the floor, going up hill. Also boost hits 15psi quick, and will slowly creep to 17 say 4th gear 2500 rpm. Stock boost supposed to be 18, 21, 22, Im not sure?

Guesses so far have been
bad APPS?
Bad Crank position?
VP (no I dont want to hear that!) fuel pressure stays above 5( usually 8), high as 16psi
Maybe the engines just getting tired? Doubt it too
Valves outta whack?

Tires are 235/85-16 if youre curious. Turbo spins nice and smooth, zero play or noise.

Am I just chasing something that nots there (just a bit worn on the engine)? Or is this all the power I should be expecting. There's a comp box waiting to go on. It did not/will not go on until the gauges were on (done now) and once the problem/issue gets taken care of, to prevent any possible damage happening.

Any ideas/thoughts, and especially experience is very appreciated!

Welcome to the site.

This thread will fix your boost issues. https://www.dieselbombers.com/cummin...tructions.html

For the rest of the issues. What kind of fuel pressure are you runnin. High and low end. Have you checked for any codes.

No codes
fuel pressure typically 14 psi. Occasionally up to 16psi, and can pull it down to ~8, though I *think* I remember seeing 5psi once?

Banjo bolt on vp maybe an issue? Just throwing guesses at this point!

Looks like a stop at home dept for some plumbing, thats a slick idea!

Sounds like you've done your reading before your post here. Great job on that. I would say that you are right on the Regulator valve bein the next easiest thing to check.

That 5psi is a bad thing though. Not life threatening but at the very bottom edge of it.

Be sure to go in and fill out your signature with all your truck info so we can see what all you have done to it already. Helps know better about what were talkin about.

Pretty sure the 5psi was with a carter lift pump. I went back to the holley, and havent seen it below 8, and even that is pretty hard to get too.

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Remembered one other thing.
Sitting at 8psi 4th gear, ~55 mph 1500 rpm, egts sit right on 1000. Seems a little high? Maybe indicates something?

The EGT's are from the boost leak. With something leaking in the system the turbo is havin to work overtime to produce power and that raises EGT's.

check all your boots going to your intercooler and from intercooler to engine you might have a loose clamp or a small cut in one of them, just throwing stuff out there. The Crankshaft positioning sensor is a mother to change. Well mine was be ready with some good penetrating fluid cause most likely the oring is all crudded up and the sensor wont come out real easy like on all the tv shows haha

That kinda makes sense why I see 15-17 creeeeeeeep slowly, but onlt at high rpm, long duration (4th gear going uphill)

Got the pipe parts, Ill be playing with this, possibly tonight!

This wouldnt affect starting though, guess there?

A boost leak wont effect starting

actually a idling motor will have no boost at all

you will have fun with the leak tester.......you will also be suprised :humm:


I tested like 7 trucks one day for boost leaks and every one of em had leaks..............including my own:ouch:

I betcha if you pay special attention to your exhaust manifold you will find your biggest leaks in cracks in it, if it's stock that is. In my case the whole bootom side was split wide open down where you could see it just lookin. From the topside it looked fine, once I pulled it I had a 1/4 inch crack about 3 inches long hangin wide open. All these stock manifolds on 98.5-00 and some even newer all crack.

The hard starting issues is gonna turn out to be a dirty sensor or a fueling system problem.