Fuel pressure & injector problems

[ChillyDog]

I installed a set of 370 injectors about 6 months ago and have had problems ever since. The truck lost a bunch of off idle power and stumbles under 1500 rpm. Before i installed the injectors I could start off in 1st gear with out touching the throttle but now I have to feather the throttle on take off or the truck dies. I bumped up the idle to around 900 rpm and it made no difference. The engine also idles really rough, I mean the whole truck shakes! Today I tried breaking loose one injector at a time to see if the idle dropped. When I broke loose the # 1 & 6 injectors there was no drop in idle but #'s 2-6 all dropped the idle when broken loose. Does this mean I got two bad injectors? Or could there be other problems I should check for? The truck really seems to scream once over 1500rpm's and the boost comes on. I also checked the fuel pressure today with the TST adapter and my boost guage. The fuel pressure goes right up to about 46 psi and stays right around there no matter what the rpm. The guage is very smooth, no pulses like i have heard of. I tried to pinch off the ruturn fuel line and the pressure goes to over 55psi. The fuel filter is fairly new, as far as I can tell no fuel lines are kinked. Any ideas? Sorry about the book here, i just wanted to explain the problems as well as I could.



Thanks,

Bill

 

[illflem]

I'm not sure if your high fuel pressure is causing the low end problem, but it's way too high(2x), sounds like your overflow valve needs replacing. What will happen with the high pressure is that system, including the filter will be more prone to leaks. Your lift pump is also working much harder than it needs and will wear faster.



I doubt if you got two bad injectors, I would suspect the injection pump. Also if you bent the injector lines while installing your 370s rather than removing them totally you could have kinked the passage closed. The passage though the injector lines is rather small, the lines are thick walled. They should never be bent as it can close them off or cause leaking.

 

[ChillyDog]

I did stretch the spring in the overflow valve a while ago because it was a little short. It made a small improvement in the low end performance. Is it possible that stretching the spring could bump the pressure up that high? I don't think I kinked any injector lines on the install, but it is possible. When I cracked the lines open to check the injectors the fuel was pouring out of all of them pretty good but #'s 1 & 6 made no difference in engine idle.



Bill

 

[Joe G.]

ChillyDog,



One way to eliminate the injectors as being a problem is to swap them with ones you know are working. If the problem moves with them then they are the problem. If not look someplace else.

 

[ChillyDog]

Joe, I was thinking the same thing but I no longer have the stock injectors. I don't want to spend the cash on a new set of injectors and find out they are not the problem.

 

[cumminsgetme]

Chilly,

If you think 1&6 are giving you problems then move them to 2&3..... then put "good" injectors (2,3,4 or 5) at 1&6... ... with new injectors at 1&6 check idle... . if the replaced injectors (which you know were good from before) still don't affect idle then you know it's not the injectors.

 

[illflem]

I think what Joe is saying is to move the injectors from the "bad" cylinders to ones that are working fine to see if the problem moves with them. That will tell you if the injectors are the problem.

You probably caused the high fuel pressure by stretching the spring too much. Get a new overflow valve from Piers, his price is half of what Dodge wants.

 

[Deezul1]

Over flow valve spring stretched to . 550 works good factory specs are . 500 I am pretty sure. Just a way to test for trouble and replace it if that makes a difference.

 

[Dennis Garrett]

I've never had the injectors out of my Dodge, but have had them out on the VW Rabbit, (Don't ask) & the old D-6 Cat. Could a speck of dirt, paint, or grit got in them before you put the lines back on?

 

[Cooker]

I have ~46psi of fuel pressue too. I have determined it is not my overflow valve. Next thing to check is a pinched return line.



-Ryan

 

[Joe G.]

I didn't stretch the spring in my overflow valve because I think that damages it. Instead I made a shim out of a small washer to get it back to the correct length. No problems since and it's been quite a few miles. My fuel pressure is higher than it should be, but the engine runs great so it must not be a problem.

 

[Turbo Thom]

ChillyDog:

I also installed 370's and have had a "shakey" feel since. I also had 300's in that did not do this and the stock 215's run smooth. I called Piers about the problem and he said the 370's were very sensitive and need to be adjusted to. Like you I stall the truck from a start, with 14k. I can just get it rolling I have no trouble. On a hill that sometimes is difficult.



What is your timing? I wonder if the pump could be putting out more with the 370's than 16 degrees will work with.



I bought the wife a 98 with the Banks power pack on it and that thing pulls from 1200 rpm. Twin air ducts and a 14 cm housing. It smokes more than mine but she said she likes it like that. It's used as a horn after she passes some "jerk".



If you find the 370's stumble fix, let me know. If I can't I'll go back to the 215's.



Thanks



... Preston...