Hesitation with DTC 18 & 35

[batman1999]

My

[gmctd]

Welcome to the forum, and what are your cold ambients and what type fuel r u running?

[batman1999]

I'm in North Carolina so the temps are moderate. The problem does not appear to be seasonal - happens summer and winter - so the temp range is something like 20 to 60

[gmctd]

35 can be caused by low fuel, bad fuel, bubbles in fuel - could indicate the OPS is not powering-up the lift pump till block temperature rises above a certain level, or the lift pump doesnt run well till it warms up.

Open the water drain tap while engine is running - fuel should pour out without killing engine.

Could indicate requirement for fuel additive in low-useage truck.

The 18 code can be caused by the OS filter - rectangular 6-wire module - plugs into the OS harness.

Or, both could be caused by poor grounding - check battery cables and all grounds for oxidation\corrosion and loose\broken wires.

[batman1999]

I don't get any fuel at the drain valve. Left valve open until engine stalled. Tried with and without fuel tank cap on. What should I try next?

Cleaned the grounds but I haven't road tested yet since I found a fuel problem.

I'm OK with using a fuel additive - any suggestions??

Thanks

[gmctd]

Welcome to the forum.......

Do a search here on Lift Pump LP and Oil Pressure Sensor OPS - it's one or the other or both

[batman1999]

The OPS was the cause of the lift pump issue. The lift pump runs properly now (after OPS replacement) and has good flow and pressure. The truck has greatly increased power with proper lift pump operation.

Unfortunately my hesitation (stumbling) problem has not been solved. I've gone through the stalling/DTC35 procedure found here in the Forum up to the point of pulling the intake (I'm trying to avoid that if possible). No help yet!

This issue is so predictable - only early in a trip - it seems to me that it has to be temperature related. I drove the truck about 200+ miles today. Stumbled only once about 10 miles from the cold start. I erased the codes (18 and 35) right after they happened - did not occur the rest of the day.

Still Looking!!

[moondoggie]

Good Day!

You might want to take a peek at DTC 35 - Help! (http://72.22.76.69/tdpforum/showthread.php?t=22757) (Click in colored text).

Blessings!

[mjv88]

I am a newbie here to the diesel page. last winter spring i was on the othe place for a while, never got my truck running so i parked it until now. i talked to someone at peninsular diesel and they strongly recommended joining this sight,so here i am.

I have read quite extensively on this thread about the dtc 35 and the grounding issues associated with that. what about the dtc 18?

let me back up a bit. like i said, last winter when my truck first experienced problems is was just a no start. i actually burned up a starter trying to start it. i did some reading and found that the pmd or the fsd was likely the culprit, or was made to believe it was? so i obtained a fsd and a fds cooler, remote mounted it to the top of the intake manifold, remember this was winter time and i was doing no pulling so heat really shouldnt have been an issue. anyway that worked for about a month. even seemed to have more power than before i changed the fsd.

then one morning, it wouldnt start. and when it finally did i had to keep my foot on the acc pedal or it would immediately die. i had to do this until engine warmed up a bit, after that it would idle. The codes the truck was throwing then were 35, 36, 54. i finally had to just park the crate because i didnt have the money to fix it. i just pulled the batteries and let it sit all summer

now i have it back in my shop and it is throwing dtc 18 and 35. it will start buty i have to keep my foot on the acc pedal or it will die, do this until warm and it idles fine. go to drive it and it is definetly in limp mode. no power, very little acceleration and no shift unless i let off the acc pedal.

i have been checking grounds and all appear to be fine. fuel filter has been changed, fuel is good, have good fuel pressure, lift pump works fine, fuel shut off selenoid on IP is working, retorqed the fsd to cooler plate. Any other ideas?

[DmaxMaverick]

Welcome to the Forums, Mjv88!

Your issue is not unique. If you can get it running under any condition, even having to floor the pedal, you can just about rule out electronics. While the PCM could be causing it, it is very rare. Don't rule it out, though.

Your problem sounds like a fuel supply issue. Could be a fuel line blockage (supply or return), suction air leak, lift pump (either intermittent operation, or growing weak), blocked fuel pick-up line (plugged sock), fuel filter, and even biological growth in the tank. Your fuel pump could be going south, as well as the IP. The best approach is to closely follow the diagnostic steps HERE (http://www.thedieselpage.com/password.htm) (links at the bottom of the page) to eliminate what is working properly. Most of the articles require a subscription, but well worth it. You could try a hit/miss approach with the discussion boards by posting questions/results, but the diagnostic steps will quickly get you to the root of the problem, and stop the wild goose chases. Gaining access to these resources is the best investment you'll make for your 6.5.