Ok so these last few days have been very very cold where i live temperatures from -25 to -35!!! The first day it was 20 deg F, and i went to start the dmax and when i tried starting it i cranked it and it started for a min and then died? i tried again and it didnt start in the 3 sec it usually did, i waited a few seconds and tried again and cranked for like 10 sec like 5 times and still wudnt start and it wasnt even that cold? I plugged it in for 3 hours and tried starting it again and nothin, so i primed it a few times and tired again and it started right up. Then the next morning i left the truck plugged in all night and it was -30 and did the same damn thing, i primed it till it was getting harder and for some reason diesel started leaking from around underneith the filter? i cudnt see where the leak was coming from cuz it was dark and i was freezing my a$$ off but i got her to start. The truck has a new fuel filter on from like a month ago, and it started giving me problems these last couple of days when its been super cold, before this cold its been starting like a champ. What cud be causing this and i am using a additive to avoid fuel gelling.
The WIF sensor is cracked-- if it is leaking from the bottom. They are plastic and a common problem. I got a special plug from Merchant to replace the sensor, and will never have that problem again.
Check for the leak in the day time, if it is only leaking at bottom then it is the WIF but could also be the seal at the top and needs to be tightened. WIF sensor should only be HAND TIGHT,
A good anti-gel is Primrose Oil Company, Dallas Tx item #4033 which also works with bio blends and pure B100. Very nice people, ask for Thomas.
Ya im going to check it out today, im really hoping its not the WIF sensor cuz ive heard those are 60-100 bucks just for that piece. If it is that where cud i get a WIF at or heavier duty one?
Ok so if i get the MA plug then how do i hook the wires back on? Or do you not need to put the wire back on again Oh and i happen to have the PPE WIF wrench wud my wrench still fit on this MA plug????
so basically the benefit of the billet plug is it doesnt leak anymore... would you only recommend replacing it if it leaks? kinda like if it aint broke, dont fix it?
The WIF sensor does not always work. Many have had water in the filter and it never triggered the light. I have a good pre filter that also holds the water.
If the wires are disconnected, it in no way affects the running or the electrical system. Yes, the wrench does fit the replacement plug.
Awesome thank you guys you have been super helpful i appreciate it very much, im def gonna get that MA Plug for sure. So then by leaving the wires disconected i shudnt notice a difference at all? Will the sensor light not trigger being disconected then? This sounds like a sweet product
leaving it disconnected won't trigger the light. Last time I priced a WIF at the dealer they quoted around $40. We have not replaced a WIF since we quit using the wrench at the shop. A cracked WIF is from over tightening, should be only hand tight, that is all it takes, same with the filter. We have had some filters that were tightened so tight that when we tried to remove them, the plastic inside the metal housing would strip away from the outside housing and the filter won't spin off. We have been lucky so far in being able to remove them when this occurs. Should you encounter this problem, take a flat blade screwdriver and lightly drive the metal into the plastic, do this in 3 places just for good measure and it should spin off.
Well i took a good look at my filter today and found out that my WIF sensor is ok not cracked at all, but when i prime it diesel starts dripping everywhere on the valve cover. The leak is coming from around the filter housing, it leaks on top of the valve cover but a cant see where it is coming from exactly cant fit my head under there lol, i think i may have a crack around the top of the housing somewhere, its pricey to get a new one they are like $300 :O
Check the filter to see if it is tight, also check the hoses.
Do you have fuel on top of the filter housing or just from the filter mating surface down.
What brand of filter do you use?
We have seen one filter crack and leak because it was over tightened, changed the filter, problem solved. You might try that first and if the problem still persist, remove the filter head (2 bolts) and inspect for cracks. A new filter head is available from the Dmax store that fits 04.5 up for $100. The only difference is the tubes for the hose connections are different. A length of hose solves that problem, you might also check ebay. I have purchased 2 filter heads for LB7's from there and they were quite reasonable, around $65ea incl S&H. The reason for cracks in the filter head, filters or WIF is over tightening. Filter should be hand tight + no more than an 1/8 turn, WIF should be just hand tight.
Good luck, let us know what you find.
I'm trying to fix an 02 LB7 that's very hard to start. Code P1094C. Checked for air on low pressure side, ok, checked priming pump, ok, checked for leakage at FPR, ok. Regulator flow @ idle is all over the place...800-5400 mm3. 54 ml fuel @ return line in 15 sec. 18ml RH bank, 30ml LH bank. Pulled LH cover, all injectors returning 3.5-4ml in 15 sec crank. Haven't checked RH bank yet. I have very little experience with Duramaxes and need help determining if all these injectors are bad. Thanks
I've never seen that code before, and it's not in my DTC list, though the P10XX series involve the fuel system.
Fuel rail pressure should be ~4000psi @ idle and depending on programming, ~26,000psi @ WOT.
I would start with a balance test to rule out injectors. Balance rates should be 0 +/-4 (-4 to +4) in park, and 0 +/-6 in gear with brake applied.
Also, since you're new to the DMax world... a simple fuel filter change solves 90% of the problems with these trucks. It's poorly designed and needs changing often (4000-6000 miles is all I can get before I notice performance loss).
New filter head & filter from GM. That was my first test. Could get 10 psi w/the priming pump, but it fell off to less than 2 within a minute. I thought it was a bad check valve in the filter head. Didn't fix it.
No P0087 or 88 in history. AC Delco Filter. Checked for air on low pressure side, ok, checked priming pump, ok, checked for leakage at FPR, ok. Regulator flow @ idle is all over the place...800-5400 mm3. 54 ml fuel @ return line in 15 sec. 18ml RH bank, 30ml LH bank. Pulled LH cover, all injectors returning 3.5-4ml in 15 sec crank. Haven't checked RH bank yet. I have very little experience with Duramaxes and need help determining if all these injectors are bad. What do you think?
What brand of code reader are you using? Some are able to retrieve history but most don't.
At any time in the last 2 or 3 filter changes, did it have the new Wix 33960 series fuel filter? When that filter becomes restricted, it can cause problems.
Some of the 01-02"s had a problem with the fuel line rubbing the body or frame and causing a pin hole. The pin hole doesn't necessarily cause fuel loss, however, it does allow air in the line. A friend had a new 02 with 30,000 miles on it that would not start on its own unless it was primed before starting, then it ran fine until it sat for over an hour and then he had to prime it again. It took the dealer 6 mo to find the hole after they had replaced injectors, CP3, filter housing and injector lines. Once they located the pin hole (body rubbing on the hose) and replaced that section of hose, the problem was gone. As of last week, the truck had over 200,000 on it and not another fuel related problem since the hose repair.
As far as the flow of the pump and FPR, that can be affected by air. A more accurate measure of those two would be pressure readings. First thing I would do would be to pressurize the tank (no more than 5-8 psi) and have an assistant bleed the system at the schrader valve using a catch can. Once the air bleed is done, continue pressurizing the system and check the entire feed line from the tank to the CP3 and out to the schrader for a fuel leak. Schrader valve is the black cap located under the alternator and is at the end of the line past the CP3. Bleed off at least a gallon of fuel so you know all the air is out and go from there. It is a simple proceedure and one of the first things we do when there is a starting problem and nothing really stands out. If you have one or two bad injectors, the truck should still start. If you have a bad FPR, the truck might or might not start and then idle with a lope or make the injectors knock. Do the bleed to the schrader valve then take some pressure readings and let us know what you find.
A good investment is the factory manual. They are year and model specific, looks like 5 phone books and available from Helm Inc for around $150...well worth it when you consider what the dealers charge.
Just had the exact same prob. My truck actually died on the side of the road like i ran out of diesel and through some troubleshooting i was able to get it started by pumping the primer while my wife turned it over and it would crank but only run a few seconds. i too noticed diesel drippin and assumed the WIF, turns out it was the bleeder screw on top of the filter, they are plastic and hollow (great idea right?) anyway replaced it and truck has not given me a hiccup since.
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