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New engine, first stall....

DieselSlug

DieselSlug

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Fabius, NY
Welp, about 600 trouble free miles, until today... Truck stalled while i was going about 20mph, just died. Like someone turned it off. THen on the way home it did it again. Pmd remote mounted, less than 2 years old, clean fuel and filter, grounds are all good, done them before. Lift pump is under 2 years old also. Im thinking either OPS (i reused my old one), or i also found out i am getting a real bad vacuum in my fuel tank. I twist the cap and it will suck in air for a good 4 seconds or so. SO i drilled a hole in the center of the fuel cap with a 7/64th's bit. Got home and it is still holding pressure, not quite as much but still a lot. Gonna run with the cap loose for a while see if that helps. I would think it would be the vacuum thing because it only does it when ive driven it for a while (bout 20-30 min). We will see, any other opinions appreciated.... Too good to be true.... And of course i have a spot for a fuel pressure guage in between the fuel manager and the i/p, but funds are zip so its just plugged right now with a cap....
 
Well, at least you still know its a 6.5 :)...

Having vacuum in the tank must mean everything else is flowing more than adequate, wouldn't ya think? Including the sock not being clogged....

You running a gasoline cap?

Try running like you said without cap, see what happens.


Once you have a fuel pressure gauge installed you CANNOT drive without one..... sux not to have one. At least you're all tapped in for when you can grab one. Even a 10buck tester one you can hook up to ideal spot easily.
 
DieselSlug said:
No the cap says diesel on it, so for now im just going to thread it on one or two threads....
Click to expand...

I have done that for years. no matter what cap I bought the never vented, so i just leave them loose
 
OH, btw i have a nice tester kit, paid like 30 bucks for it, but with this being an intermittent issue it is never there when i hook it up....
 
Just did a best offer bid on a mechanical liquid filled fuel pressure guage on ebay, 12 dollars.... I already have the same one on my car...
 
Matt Bachand said:
You ever load up the plow yet to test out the timbrens and make sure you dont' have any wiring bugs?
Click to expand...

No, havent had time, now that the truck been running its spent more time with me where i go rather than home... LOL Now that it runs i got to get out while i can!! I will try it soon, i am actually having problems with my front shocks. They are too short:eek:. I lifted the truck 1.5-2 inches, and they are bottomed to full extension!! I hope i dont blow one! I dont have money for another set...:mad2: Not good...
 
Can you elaborate on the "like someone just turned it off"

Do you mean all the interior lights went out and radio turned off like actually happens when you turn it off? Or did it just stall?

If it did act like it turned off then would be looking for an ignition issue.

Check the lower left pin of the OBD1 port for voltage while running, if its at all less than battery voltage then the OPS is starting to go and you should really put a real automotive relay on the LP triggered by the OPS instead.

If not where did you get the PMD extension cable
 
directly from the mouth of Bill Heath:
the cap is not supposed to vent. the vacuum in the tank is there for a reason.

i had the same symptoms when i had the leak in the fuel lines.
the reason the "drilling" or leaving off of the caps helps in such instances, is that without vacuum air does not get into the lines as easy.
but this is only a temporary fix.

read up on my miami story in the lupoblog, there is also pics. it was the lines right above the tank where you could not see them. all rusted out. it took me forever to diagnose and i was about to replace sock also when i dropped tank and found the lines.

as always bill heath diagnosed it over the phone in 5 mins and was darn right all along, but i could not locate any fuel leak so i was just going down the list of what else it could be.
 
Oh, why is it supposed to be vacuum in the fueltank? I always heard no vacuum in there.

Trond
 
Vacuum or no vacuum, that is the question. :D

With so many differences of opinion it seems like no definitive answer has been provided. From what I have read, a slight vacuum is meant to exist; however, I have also read many posts, like DEERE's and others, that show a non-vacuum system works just fine (i.e. keeping the cap loose).

IIRC, KNKREB had a great thread on this at the old site (I think it was linked to the reference stickies.) He made the case that too much vacuum is to be prevented by a vented fuel cap, then others chimed in that even with a vented cap they had vacuum, and then GMCTD stepped in to lay some science on the table. It is a good read!
 
sub6291 said:
Oh, why is it supposed to be vacuum in the fueltank? I always heard no vacuum in there.

Trond
Click to expand...

The vacuum there is to prevent sloshing, and frothing of the fuel, from driving and the return line. Its for stability, kind of like why race fuel cells are filled with a type of foam. There should be more vacuum as more fuel is used up, acting like a baffle.
 
I have a 34 gallon tank and usually run it down to about 5 gallons and there is always a lot of vacuum when I go to fillup, and dont have any driveability issues. If you have a full tank and only driven about 20 minutes and you have loads of vacuum there is an issue.

However my bed auxiliary fuel tank plumbed straight into the fuel lines with an elctric solenoid to choose which one is used never has any vacuum on it, not sure what it does to vent or what not, but it works fine, but I do notice a lot more movement on the fuel gauge on bumps and hills and turns from the auxiliary tank, which could also be due to its dimensions and location.
 
I thought the vacuum was more for emissions purposes. My fuel still sloshes bad with or without the cap, stupid cheap aftermarket sending units!! Anywho it did not solve my problem. The truck stalled on me 4 times today. Everything in the truck stays on (lights and radio), just the engine shuts down. The truck has a new turn signal switch, ignition switch, and ignition key switch. Did those the beginning of this summer due to a different problem that turned out to being the soleniod on the starter. But i bought a Premium (not the cheaper version) of NAPA's OPS, i know, i know, buy only GM, but i need this truck, after dumping 4g into engine work i need some time to recover. So i paid 30 bucks for it. Put it on and so far no stalling. (Knocks on wood). I will keep all posted, drove it for about 30 minutes to home, then 20 to work and it hasnt stalled yet. I have my spare PMD's in the back. Going to do all the tests this weekend if problem still persiste, no time right now...
 
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