1999 isc 330 hp no boost pressure

[diceman1530]

Will a bad lift pump cause no boost pressure do to lack of fuel?
Will a bad boost pressure sensor let the ecm deliver enough fuel with out reading boost?
New to diesels,I have low power so I installed a VMS to see if I could spot the problem and I have no boost pressure,the hoses all look fine and the waste gate is working.
Any ideas would be helpfull
Thanks Ray

[Triker56]

Sometimes the VMSpc will not read the boost pressure.
It never has on my 99 ISB.

I never knew what my pressure was until I put the Banks PowerPack on and it came with boost gauge.

Using a bad lift pump will soon cost you a lot of $$$$ to replace the injectors pump.

I just had the low pressure lift pump warning kit installed on mine.

Your best bet is to suck it up and take it to a Cummins shop near you. And hope they find the problem in a short time.

[J Walker]

VMSpc has a sniffer to show what parameters are available on your engine. Does the turbo boost show up? You could call Cummins Customer Service with your engine serial number and find out if you have a turbo boost sensor.
How do you know you have a bad lift pump? Lack of power could be due to many things. Something easy thing to check is the fittings on the turbo connections and the intercooler. Let us know what you find out.

[Steve Ownby]

Hey Ray,

Did your low power just happen suddenly? What hoses are you referring to that look ok? I am surprised that your '99 Alpine doesn't have a boost gauge.

There are 4" flex connections made of high temp silicone either red or blue which connect the CAC to the engine intake plumbing. A small hole in one of these will seriously impact your level of boost and your power level. Inspect these carefully.

Good luck,

Steve O

[diceman1530]

I have a vms el320 and not a vmspc and it never shows anything above
"o" boost.
It does have a boost sensor that i am going to replace as soon as it comes in.
I checked all the silicone hoses on the inlet, not real good but with zero boost I felt it should be somewhat easy to spot.( could be wrong as I dont know much about diesels)
Just fishing for ideas before I send it somewhere to get fixed.
Thanks Ray

[rmmpe]

Hi Ray.

I see you've been communicating with Mark O.

Mine had a similar problem at the front port and Mark helped me troubleshoot it over the phone. Since then it's worked fine (VMSpc).

You should be showing some boost and I suspect it may be a bad data feed.
Do you hear the Turbo spool-up?
When accelerating, can you feel a power surge at about 1400 RPM?

E-mail me at rmmpe@yahoo.com

Bob

[diceman1530]

replaced boost pressure sensor still no boost pressure on vms
put mechanical gauge in inlet and have normal boost pressure
hooked up cummins scanner and it reads the boost pressure
(went to 19.5 on test drive)
with the scanner hooked up the vms shows the boost pressure also
next checked the fuel pressure out of the fuel filter and lift pump 20psi but drops to 15psi under load
anybody know what those numbers should be?
Thanks Ray

[EngineerMike]

Ray- your fuel pressure numbers are good. You need enough to keep the injection pump from starving for fuel which is its internal lubricant; 8 or 9 psi is sufficient for that.
You might still have a boost loss. I don't think a torn elbow would be overly obvious on a visual inspection, but they usuall break on the seams, so a tactile inspection should be useful for finding a rip. I don't know for sure what your top boost should be but I'm guessing in the 30's. If no torn rubber parts, the charge air cooler (CAC) could have leak(s). I think that has to come off to be tested, but you can check w/any good diesel shop on that (as a min. it needs to be capped on in & out with a gauge added to log pressure drop over time). Before monkeying w/that, I'd find out what your max boost should be, and under what conditions, from somebody who is more than guessing (like I am, tho based on what the ISL's see).
How is your fuel mileage? Power? If those are A-ok, maybe this is all academic.

[bborc]

My 07 ISC 330 boost runs 23 lbs max preesure and cummins dealer says that is right.

[diceman1530]

I checked the turbo psi at the turbo and at the manifold and there was no drop in pressure.( mechanical gauge and ecm) I was told but havent seen in writing that max boost is 22 to 23 psi on the ISC 330 8.3. Going to try to check the injector pump pressure next.
We are going to talk to a fuel pump guy and find out what the pressures should be.

All my lines and elbows are steel to and from the intercooler to intake with 4 small sections of silicone hose about 6" each

[Triker56]

The low lift pump pressure warning kit they have.
Is set to warn you when the pressure gets below 5 PSI.

The Banks PowerPack Turbo will get you up to 33 PSI

[diceman1530]

Well we finaly found it,a barrametric air pressure sensor, installed a new updated version.
When I test drove the coach and stood on it, the VMS showed
330 hp and 950 torq compared to a best before of 206 hp and 612 torq. Apparently that sensor put the computer in a limp mode so it would run but not what it should.
Thanks to all for the help !!!!

[chasfm11]

I'm glad that you got it fixed. If possible, could you share with us how you found the problem? I would expect the ECM to set some sort of error code if a sensor wasn't registering at all so I'm assuming that it just wasn't performing correctly. I've often wondered if there was a way to detect "limp" mode on a Cummins engine. Perhaps being too naive, I would hope that there is some reason recorded about why limp mode is entered.

Thanks for any addition insight that you can provide.

Charlie

[diceman1530]

We had to go trough a couple different programs from cummins to get the computers to talk to each other,when we did we found the code for that sensor.They said only a couple of sensors would put it in limp mode. I did not have any kind of warning light on. At least she runs like she should now. They kept sending us a ambient air temp sensor and not a barametric pressure sensor, there was some confusion with what was in there.