CUCV Wont accelerate Wont rev in neutral until RPMs creep up

[Somemedic]

PLEEZ>>> NO INJECTOR PUMP NO INJECTOR PUMP Gremlins..... just a prayer

I was driving around today and noticed a significant power loss. Truck wouldnt accelerate in D unless placed in N. Pedal was to the floor, trans in D and it wouldnt move unless it was going down a hill. After it got the rpms up it would accelerate. Seemed to run alright unless I took my foot off the pedal. When It kicked down to low idle it was rough and even died a couple times. Fired up fine. When I start it it fires up w/o hesitation and will rev (sort of) and then the idle gets rough. It idles but rough in P. Im hoping this isnt the IP cuz cash is tight. I called Chris (moderator) and at his suggestion will begin tracing down vaccuum lines and looking for leaks.

 

[ken]

You might check the rubber fuel line before the lift pump for leaks. I hard one suck air through a dryrotted hose. But since the hose was under a vacume from lift pump there was no fuel leaking out of the hose. It sounds like there is air in the system. Also make sure the advance arm on the pass side of the pump isn't sticking. Just remove the air filter and move the throttle with out the engine running. Look at the long skinny arm mounted to the passenger side of the IP. Make sure it is moving freely. If it sticks the timing advance will be off. And it will pull the same stunt. If it's sticking try some penetrating oil to free it up.

 

[Westech]

RE: CUCV Wont accelerate Wont rev in neutral until RPMs cree

well sorry to say but a vac leak wont make the cucv run like that. you can drive the trucks with out a intake at all! the only vac source is the pump and thats a stand alone system. I would start to look at the fuel filter and see if it is leaking any fuel or that it may be sucking in air in to the fuel system. that will really mess up the driveabilty of the cucv. The way you say it dies and then restarts sounds like a fuel problem to me, also look at the fuel pump on the right side of the block, look for leaks there also, check the lines all the way back to the pump. If I were going to start and toss parts I would replace the fuel filter, and then the pump on the side of the block. Thats the cheapest way to go.

 

[Somemedic]

Vaccuum seems fine. I replaced the filter with the one off the parts truck and got SOME power back temporarily but it started losing power again. Think I'll go to NAPA and get a new filter anyway.
I cant imagine why it would start sucking in air all the sudden. Something somplace may have rubbed a hole. I just dont see where theres a leak.

 

[Westech]

well the firewall mounted filter housing in the cucv just sucks to put it nice. They all seam to leak air at the place where all the wires go in to the unit. I replaced mine with a spin on unit from napa. Works really well just you lose the "water in fuel" light.

 

[Recovry4x4]

Check the lines going back to the tank. All it takes is a pinhole in one of the lines and you will have all kinds of problems.

 

[Somemedic]

Replaced filter and nothing really changed. Looks like the accelerator cable moves freely. It ran alright for a bit but the longer it ran the worse it seemed to idle. Im wondering if I didnt get some really bad fuel. Water lite never came on. More tomorrow

Thanx alot guys

 

[Jones]

Sounds like fuel starvation to me too. The cheapest place to start is to see if you have ANY filters with paper elements in the system. Replace them, especially after an extra rainy winter or heavy duty fording operations or a load of bad fuel. Most people don't realize it but the paper filter material will become saturated with water and then won't flow fuel... plugs 'em up tight and any remaining uncontaminated area will pass just enough fuel to let them run, sorta.. Maybe somebody threw an auto supply store inline filter in there so look the entire system over. I've found NAPA automobile grade add-on filters on stuff as big as 5 tonners that had to be towed in, but ran like a champ after the filter was extracted from the line.

 

[Somemedic]

I don't get frustrated easy but guys... This repair job sucked and I'm still not done.
I rerouted the the new line from the lift pump thru the motor valley and up in between the manifold and to the fuel filter base. The fuel system was pretty much together and I still had 1 alt on so I cranked the motor and primed the system. The truck really didn't even try to fire. I noticed I have a smokey ground coming off the firewall and onto one of the intake mounts. I'll clean it later. A shot of ether and she fired up running rough and spraying coolant. I ripped a heater hose moving the alt bracket over and out of the way.
It was at the very base of the hose so I cut and attached it. The truck fired up easier this time and seemed to idle as it shoud sans air filter housing. I didn't realize it before but I believe I could have confirmed the lift pump wasn't functioning by pulling the drivers side bottom hose on the fuel filter base to see if there was fuel flowing. Consequently that could only be done by cranking the motor (thought I should add that last part).
Removal of the passenger side alt is key. Everything is so much easier when its out of the way. If any of you guys have an idea on how to break that brass fitting loose post that info. That's news you can use. I couldn't so I cut the tubing and removed the pump that way. Otherwise if your completely inept at bending tube (like me) the 4ft section of fuel tube is definitely the way to go. And buying parts from Advance Auto may not be wise. The pump I received looked like a much cheaper version despite confirming this was for the heavy duty engine. After further inquiry it was learned this pump was marked to be used for the J-code motor as well as the lighter duty motor. Next time I'll get it from Chevy.
I don't mind trying to fix this truck. Its pretty easy to work on compared to others I've tried repairing. And honestly I'm not sure which is the better tools, the box of craftsmans out in the shed or you guys here on the "G" and Steel Soldiers websites. The knowledge and advice found on these sites are not only invaluable but has saved me time, money and frustration.
I'll get it back together and keep u guys posted as to the results.

 

[CCATLETT1984]

you can use fuel rated hose for that part of the system, its only under 7psi or so. I've done the pump on my truck twice, and its a pita no matter what you do. i had to replace the new one that i had put in around 6mo. later due to fuel spraying from the area where the two halves of the pump are pressed together.

 

[Somemedic]

So after all the CRAP of changing the lift pump it still does the same thing. It was working well for a few minutes. I drove it around the block and as I did things began getting worse. The symptoms began manifesting where as I pushed down on the accelerator the lesser the response.

On start up it fires immediately and will rev when u hit the accelerator, everytime. It will maintain the rpms as long as you hold the accelerator there, with lite white or maybe blue smoke. As soon as you let up off the throttle it revs down and will almost die. No throttle and it idles rough, a little more throttle to wide open is the same response, just a mild idling. I was told its probably not the injector pump cuz when it goes theres all kinds of smoke with no power. I dont believe thats the case here.

Up to now Ive never had a diesel, this is numero uno. I assume the next course of action maybe to check what kind of fuel is in the tank. My thought is this: On start up the truck pulls the fuel into the motor fine but after the rpms fall the motor cant recover. The rpms when they are high are generating enough heat and compression to burn the fuel, regardless of the fuels quality. Im getting smoke because the fuel is of substandard quality. The truck operated like it was supposed to after the repair because the fuel sat in the tank for 2 days allowing the impurities to seperate. The only hole in my logic is that the FUEL IN WATER light isnt coming on. Or maybe the filter sock is clogged on the fuel pick up. There is enough fuel in the line for the truck to run for a few moments but after that it starts creating a negative pressure lock not allowing enough fuel to flow creating the starvation. I just cant figure why once the truck revs it will stay revving until u release the pedal.

 

[dilvoy]

You can suck fuel from a Jerry can to see if the fuel in the tank is your problem, but be shure to run it long enough to get the fresh fuel to the injectors. I have the glass plunger that lives inside of the injector pump fuel returm fitting and had the same symptoms as you have. I broke the glass plunger out with a tiny screw driver and flushed the fitting out with brake cleaner and made shure I got all of the glass out, but left the spring inside. It was like a miracle cure. I have been told that this spring loaded glass plunger is to allow for easier starting, but I have had no difficulty starting without it. Return fuel from the injectors has an effect on injector pump timing.

 

[Somemedic]

Which arm of that IP octopus do I have to get it? I assume I dont have to take the pump or the intake off to do this.Anyone have a step by step idea how? I aint skeered to do it but would like to have a good idea as to how. Im under the impression that these pumps are a bit pricey when it comes to fixing them

 

[dilvoy]

The fuel return fitting is on the top front of the injector pump. It is fed by that fuel hose that arches back towards the IP.

 

[mangus580]

How many miles are on the truck? I would suspect the injection pump too. Every time I have had air in my fuel system, the engine wouldnt idle at the right RPM, it would idle way up. It also sounds different when it is sucking air.

Sorry for the bad news...

 

[Somemedic]

Took the last couple of days off. My daughter's birthday and memorial day dictated family time be made a prioity.

I plan on adding an extension piece of fuel line and running it into a fresh batch of fuel. The majority of steel line going back into the tank looks good with little surface rust. The odometer says 65k and I'm under the impression its the first time around.

Not to be a bum but I really hope its just bad fuel. I don't wanna drop the stupid tank cuz I know the fuel gauge will never work right again. I'm not crazy about messing with the IP at all but would rather try breaking a glass plunger than pulling off the intake and paying for a rebuild. However I already have the gasket kit for it. It was leaking fuel in the motor valley this winter.

I'll get back to you guys with wat the story is in a few days.

 

[dilvoy]

OH, somemedic, on my first post I was at work and talking to someone while I was typing and forgot to mention that I removed the fuel line fitting from the pump, before I broke out the glass plunger. You probably figured this out though.

 

[mangus580]

Took the last couple of days off. My daughter's birthday and memorial day dictated family time be made a prioity.

I plan on adding an extension piece of fuel line and running it into a fresh batch of fuel. The majority of steel line going back into the tank looks good with little surface rust. The odometer says 65k and I'm under the impression its the first time around.

Not to be a bum but I really hope its just bad fuel. I don't wanna drop the stupid tank cuz I know the fuel gauge will never work right again. I'm not crazy about messing with the IP at all but would rather try breaking a glass plunger than pulling off the intake and paying for a rebuild. However I already have the gasket kit for it. It was leaking fuel in the motor valley this winter.

I'll get back to you guys with wat the story is in a few days.

Leaking fuel into the valley? What was causing it? Usually, the throttle shaft seals start to leak (ie OLD pump) and let fuel drip down into the valley.

 

[CCATLETT1984]

If you determine that its the IP, i have a spare engine with one on it that you could try. It should be a good pump, engines been stored indoors.

 

[Somemedic]

ITS ALIVE!! ITS ALIVE!!!

After hooking up a aux fuel tank w/ the same symptoms I moved on to the next possible cure. I found the return line on the top of the injection pump and took off the hose. I forget what size socket it takes but I removed the "fitting" or "return line injector" (not sure what to call it) It revealed a chamber with a shrader kind of needle on top of the pump. The injector nozzle in my hand had the small glass plunger that I meant to break. When I held it up to the light i could see it was brown and there looked like there was some debris inside. I got a nail and struck it but the plunger didnt break but it did move. I sprayed it with some gumout and it moved a bit. I repeated that a few times and noticed how the plunger now moved freely and was clear. I put the injector back on and tightened the return hose back onto the fitting. The truck fired up and idled perfectly. It runs fine now except for the shift points. Theyre still to high. I need instructions on that.

Anyway symptoms were rough idling, no power, when it would rev (on start up) there was blue or white smoke. The truck would barely run and wouldnt accelerate. I hope this post helps you guys later on down the road. Thanks Ernie and Dilvoy for the suggestions and Dan too.