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.

Alright, so a little pressure test. As in could only do a little. Found a couple couplers, just tightened them a couple turns, and sealed up. The big one, is the intake. The gasket between the large intake that bolts to the head, and the thinner flat, long horizontal plate. Those are very technical descriptions! Pretty fast leak, at the back edge of it. So once that gets changed, we'll go back to rechecking the pressure, yay! :choochoo:

So how bad is that to change? Only part Im concerned about is the 3 bolt deal, right next to the APPS, just unbolt it, or? And figure a new gasket on the air horn.

As for the exh, yes there's at least one crack, and its getting longer. Was looking at both piking up another low mile used on, or an ATS (ouch!)

What is powering the Holly pump? Is it on continious with the ingnition? The vp's dont like to be pressured alot when starting. I have my Pusher pump relayed into the stock lp wire. When I key on I can hear it prime for just a second and then shuts off until I start the truck. Then its a constant flow BUT Above 5 psi i believe when starting will cause a hard start.

The truck was at one time converted to intank LP. Thets bypasses with a drawstraw and 1/2" hose feeding the holley on the frame rail, back by the tank. The relay that was put in for the intank, now drives the holley only, and the intank POS plugs the big hole in the top of the tank!

That's exactly how it should all be set up.:U:

I love dealerships... Nothing in stock, and more than double of the Cummins center in Denver.

1 check valve banjo deal
1 intake gasket
2 grid heater/horn gaskets

Looks like shipped is less than the "we can special order these parts in" guys were on the banjo itself!

Hopefully, Ill tear into this tommorrow and move ahead. Also, found a place that carries the crank sensor, MAP, and IAT, each one for less than 50 each. APPS is still pricey, so hopefully its not that one!

You can test all these sensors to see if they are good or not before you throw money at it. You can also test the regulator valve.

The valve/Banjo, just pull it out and put a nail or somethin up into it and push down on a semi accurate scale. It should be open at about 4 pounds of pressure down on it.

The Apps and all the other sensors are easy to test with an Ohm meter.

Checked out the APPS, I havent checked the others, yet. For the 25 the ball valve deal cost, I figured just replace it. the truck had a new VP on it when I bought it, it lasted 5k miles, yay! This ones been on for ~40-45k now,. Who knows, if ever that valve has been changed.

When My APPS went out it started just fine, The trick was having it in drive and having NO throttle. not sure if APPS would prevent starting....hows the fuel filter?

Just did the fuel filter, it was dirty, so brought up my fuel pressure 1-2 psi. No change in starting.

Would a bad intake leak maybe cause an issue starting? Im going to get after the ohm meter on these other sensors, and see if I find anything. And while Im inthere, swapping in new contacts on the starter! :choochoo:

The problem of a leaky intake is gonna be the introduction of non filtered air into your engine and loss of Boost. But shouldn't affect starting any. I'm holdin out hope that when you clean up, change and test sensors your gonna find you hard starting problem. If not then we move back to the fuel system.

So intake gasket was missing ~2" at the back edge. However, no change in boost performance. Im going to try the pressurizing the intake again today, so see if I find some other huge leak.

But get those thinking caps out for another idea! Valves, low compression? :argh:

waste gate stuck open???

Exactly what Im about to check, have visegrips on the hose now!

Gonna be a cracked exhaust manifold. Cracked on the bottom side where you can't see it.:pca1:

Checked from the underside, flashlight and creeper, can see the whole thing! Even went so far as to poke around with the dental mirror in other nooks and cannies! There is cracking, but only very, very thin ones. I actually checked for leaks. sprayed with soapy water, start truck, look for bubbles before it gets warm. The cracks arent even leaking the whole length, just little spots.

Now on checking voltage and ohms on MAP and IAT... Ive got 3 wires on the MAP? Im guessing there's a wire easier to stab (similar to APPS adjustment) Anyone know which ones they are and where? Im having a bear of a time trying the get a probe into the IAT, and the MAP, well, I guess I could stab all three... But none of these are easy to get to back there!

The wire you probe to check the APPS is on the firewall. The other 3 sensors have to come out to check them. Your just checking resitance on them and not actual current runnin through them.

Those cracks on the manifold will open up under pressure.

I'm on my way out right now but if your still havin issues when I get back I'll hunt down the instructions for these.

Duh, forgot about just taking out the sensor, plug it in and check. :ouch:

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Hmm, since the manifold is junk anyway.... Maybe Ill give it some love ala MIG, and see if I see any improvements. :humm:

Here's the full article for the APPS. https://www.dieselbombers.com/24-val...tomy-apps.html

IAT Sensor. https://www.dieselbombers.com/24-val...at-sensor.html

MAP Sensor. https://www.dieselbombers.com/5-9l-2...-pressure.html

Turbo actuator condemned. :booo:

hits 22psi (didnt try to take it farther) nice and smooth and quick. On my local test hill, EGT's also dropped.

Now to stick the banjo in, and chase the hard start issue!

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Nuts, I was hoping... Looks like a waste gate actuator is needed. Interesting though, is the Edge guy mentioned some people just plugging the waste gate hose off, but Im worried, high RPM, long hills would create too much boost. Am I nuts, or should I just plug the line off?

BD sells a nice aftermarket wastegate.

Yay, more fun. Actuator, none, anywhere, that Cummins can find! :booo:

Sooo, anyone put a bigger turbo on one of these that has an actuator they want to sell!? :howdy:

for the money, id go to a banks dealer, the banks aftermarket wastegates are on sale right now, you can get the banks quickspool housing with it for 350 bucks shipped!

No doubt, that would be sweet. But this also isnt my toy, its what hauls my toy, so it only has limited funds on how cool it gets! Plus, looks like (have to put it in and test) I have a good one here now, for free, from a buddy running a hx35 variation on his mustang. :yeah:

whatever works. so whats your toy?

Keeping this updated:
Tried another actuator, worse, went to 12psi. OS swapped back in the weak 15psi one, and threw in the edge elbow. Much better. Then wired in the comp box, without the pump wire tapper, set it on 1-5, drives great, boosts to 23psi right now. Backed it down to 1-3 see if the mileage improves. But, pulled ~4-5k over 11k ft pass, pulled great, topped the pass at ~65, and only half throttle.

Plans now, turn off the box, take out the elbow, adjust the actuator to get it happy, back at stock settings. Then back in with the elbow, tap the pump wire, and be good to go.

As for the toy:

e, my nieghbor down the road has one of those rock crawlers, he taes it to the 4x4 jamboree in Indianapolis every year.

So boost elbow stuck in, and comp box set on 1-3, with pump wire untapped.

Varied on towing from 12-14.5mpg, however unloaded is up to 18.5, up from dea-on-always 17. Boosting at 23 psi. Playing with the actuator a bit more, and se if I should be boosting more or not. Then Ill tap the pump wire and call it done.

On the hard start, appears either fuel pressure or apps related. If I do key on, pump throttle, then bump the starter wait for 4psi, starts right up. However if I just pump the throttle, hard start still. And sometimes if it just gets the bump to 4psi, hard start. so thinking 12-15 psi is just a little too much pressure for the vp44 on start up.

Compared to a couple months ago, runs great!