Just wondering if anyone has any Idea's. We Just got done with another conversion. cyl 3 and 6 are not firing. If you crack the line on either one they spray fuel real hard more than other cylinder, and there is no change in engine. Today we pulled the injectors and had them tested, and they are popping off when they should. We also cranked the motor over with no fuel and it dosen't have any easy spots.


PLEASE HELP!!!!!!!!!!!!!!!!!!!!!!!

 

Did you try to swap the injectors to a different hole to see if it made any differance? I would also pull the rocker cover for those two cylinders to make sure the vale lash is ok and to check the rocker movement.You say those two line are spraying more fuel than the rest?

 

I was just working on a toyota 22r this weekend with two dead cylinders. They had tight exhuast valves leaking all the compression. Damage was already done on one of them though and it is burned out.

 

yes they are spraying fuel harder than other lines, like they are not popping off. But they where pop tested today.

 

If it was a valve prob wouldn't you feel/hear easy spots in the engine, while cranking over without any fuel going to it?

 

I thought of a few more things, If it has fuel , the injectors have been tested, if you verify valve lash and operation, the next thing would be compresion. we all kow how how a diesel is fired off of cylinder presher, well the compresion ratio is somthing like 18-1( dont know exact amount). If you had a head gasket leak of some melted pistons,it would lower that ratio to a point where it wont fire anymore. since they start with such a high ratio, even if it was down to like 12to1, it would still sound pretty normal just cranking it over, but it would be to little cylinder presher to fire that cylinder.
I dont know if there is a way to test the compresion on these moters or if you just have to pull the head? I am sure some one will chime in . In any case I would exhaust all other options first then pull the head!

 

on a possible valve problem , you might not always here it, just like if you turn the engin over slow and the presher leeks past the rings, it sometimes does not have much sound. I would defintly check the valve operation as well though, broken rocker, broken valve spring, flat cam lobe, ect.

 

Any Diesel In the oil? Take out the dip stick and smell it. Also you can get a compression tester that screws into the injector holes.

Brenden

 

If you have the correct compression tester it easy, pull the lines and injectors out and do them one at a time. It needs to clamped into the injector bore because mine has around 380 psi at cranking rpm's and I don't recomend holding tha by hand.

If you don't have a compression tester you can pull the injectors from the offending cylinders and try a leak down test with a good rubber tipped blow gun. Piston needs to be right on top or bottom with the valves closed. It should give you and idea if a vavle is bad.

Its interesting that 3 and 6 are dead, the firing order is 1-5-3-6-2-4.

 

yeah with that firing order 3 & 6 scares me..

 

I think the first thing would be to swap 1 and 3 injectors and 4 and 6 or something like that. Then do a compression or leak down test.

 

check for bent push rods

 

Can you get it started?the reason i ask is i just did some pump mods on one and it was not firing on 2 cyl. (want to say 3/6 ) dont remember which ones but the two injectors were air locked, it was wierd, the only way we got it to fire was to take it out with the miss and ran it hard down the street it came back runnig fine . hope you get it going

 

12valve these monsters have so much compression you'll never feel an easy spot. Check valves and do compression test, that be my best bet.

 

Well fellas thanks again for all the Ideas. The Truck is now running fine. I am not shure what it was, we said forget it and took it down the road for it's maiden Voyage and it ended up smoothing out. Every once in a while you can feel a slight miss, but it is hardly there, I think the old girl just needs to be ran a little.