catd69u

I haven't got to work on it lately, but I think I'm gong to run a compression test before I do anything else. I've been over the fuel system, and I can't seem to find anything wrong. It won't start cold at all without a shot of ether. After it's warmed up, if I shut it off and quickly start it right back up, it will start, but it cranks several times before it fires back up. If it cools down, it has to have ether. It runs great after it starts. I've never seen a 12 valve act this way before. I own three, and I've owned one of them 17 years. What do you guys think about checking the compression? I don't know what else to look at........................

AlpineRAM

Maybe your starter rpm is really low... Aftermarket starter, bad wiring etc.
A compression test is always good, but the results depend on the starter rpm for the same engine.

catd69u

I have put new batteries in, and the starter whirls it plenty fast.

AlpineRAM

OK, that's something that is overlooked quite often.
Does the truck start if you go full throttle while starting?

catd69u

Nope. It won't start at all when it's cooled off all the way. Just cranks and cranks. After it's warmed up, it will start back immediately but cranks way more than it should. Doesn't seem to matter if you throttle it or not.

AlpineRAM

Did you check if you have fuel after cooldown? just open injector lines and try to start. If there is no fuel this points towards an air leak in the fuel system, if there is fuel it looks like a compression test is the next step.

Sittingbull2

I am going what others on here have said. Primer lift pump has check ***** in it and they could be stuck allowing fuel to drain back and causing your problem about not starting after a few hours of not running. Hence you having to shoot ether in it to start. If you still have to do that at least try wd40 instead of ether.

AlpineRAM

Since he says it's hard starting immediately after being run and impossible if you try it after a short time... I think it must be some rather big air leak.
Either return system from the injectors or the suction line to the lift pump.

Loss of prime seems to occur at a speed that manual operation of the LP and operating at starter rpm do not net sufficient fuel flow to overcome the loss of prime- only the rpm increase firing up with ether nets enough fuel flow.

catd69u

You guys have given me some other things to think about. I don't know exactly when I can get back to it again, but when I do I'll report back on what I find. Thanks for all the replies........

catd69u

I thought I'd let you guys know, I done a compression test yesterday, and it's got 0 pounds on cylinders 1 thru 4. I didn't bother to check 5 and 6, cause I figure I've found the problem. I don't see how it ran at all, but it would and does run after a shot of ether. I guess I'm in for an overhaul. Anyways, I want to thank everybody for all the replies. I appreciate it...............

Barry

AlpineRAM

Really zero psi? Quite unbelieveable, never had a diesel run without puking all it's oil from the crankcase breather within minutes if compression was that low...

Just for grins and giggles- did you check the valve clearance?

catd69u

I haven't checked anything else yet, but if the valves were that far out of adjustment wouldn't it missfire on those cylinders? When it runs, it runs perfect. It's just hard to start. I checked it with two different test gauges to make sure, and all it will do is wiggle the needle when it cranks. I still don't understand it myself........................

AlpineRAM

Getting your exhaust valves (all of them) to about 0.05mm negative clearance will have you lose enough compression to be unable to start, but only a little less power while running. (Until you burnt the valves due to insufficient seat time to cool)

Easy peasy test- use compressed air and get it into the cylinder with the compression tester fitting. Listen to where it whistles. Maybe remove the turbo. (to check on the exhaust side)
Maybe remove the intake runner plate and watch your valves.
You will need to rotate your engine to compression TDC of the cylinder you want to test and block it there (it will want to turn rather forcefully)

catd69u

Thanks for the suggestion. I'll check this closer before I do anything else.

catd69u

I got #1 cylinder on tdc, and took the valve cover off to make sure the valves were closed. Compressed air flows freely through the cylinder, and sounds like it's going in the crankcase. I took the oil fill tube off, and when I cover the hole with my hand, the air sound changes. I'm pretty sure that's where it's going. I may check another cylinder or two when I get time. Doesn't look good.