injection pump ?

[DanaLittle]

how can you tell if you have a weak injection pump ? I've got my full fuel screw all the way in, star wheel all the way down, oldsmokey fuel pin, 16cm exhaust housing on stock turbo, full 4in exhaust with no muffler. I get very little smoke on acceleration and my egt's at 70mph on level road only get to 350. Could the IP be weak and not suppling enough pressure? Could it be the lift pump ? I just thought with my full fuel screw maxxed that my EGT's would go sky high and it would smoke more. Any thoughts. I have never had any EGT problems either. sorry so long winded. Any info will help.

 

[BushWakr - RIP]

Hi Dana,



The first thing I'd check (assuming you haven't) is the guide pin function. This little pin sticks out at the bottom of the AFC chamber.

It protrudes and ride's up and down on the AFC cone. This thing can get sticky/stuck and that will produce the symptoms you describe.



To check it you'll need to pull the top of the AFC housing off and remove the cone assembly. When you pull the cone out have a look on the front facing edge of the cone... do you see a shiny mark (witness mark) were this pin has been rubbing/riding on the cone?

That is your first check, next once you've got the cone assembly out, look down into the open chamber and slowly cycle the throttle to WOT position.

As you cycle it the pin should pop out from the lower front edge of the AFC hole.

If it doesn't come out then there is a good chance that this is your problem or at least part of it.

There are a number of good posts on how to free this up if it's sticky, just do a quick search for posts on topics like; "sticky fuel pin" or sticking guide pin.

That should get you started at least... . good luck. .



pb...

 

[DanaLittle]

Hello Pastor Bob



I checked the guide pin and it moves freely. The fuel pin has the witness marks on it from travel. I put a new EGT probe in and temps are the same. Any other suggestions? Do you think it could be the lift pump not suppling enough pressure to injection pump ? Anything else i can check? I'm i just expecting to much out of the stock injectors? The truck runs good. I can get 25psi out of turbo and average 18-19 mpg. I guess i just want to be sure everything is ok. Thank for our input. Dana

 

[1stgen4evr]

Aside from adjustments as the good Pastor mentioned, the pump is weak when it won't start up well. You have a plunger and barrell that fits with micro precision. When it is worn your first signs will be poor starting. Beyond that, you have to adjust the various elements for max function. JLeonard probably will email you a manual on the pump if you say please. It would be useful to study that in your quest for max performance. There are some very good descriptions and photos that will help you understand the pump. Most of the other things that will/can go wrong will leave you dead in the water or at the least with a noticable skip.



James

 

[TKingsbury]

Is your pyro in the manifold or downpipe? My boss says his old 93 was the same way, really low pyro readings. His was in the downpipe and his truck was stock. I never saw readings that low with mine in the downpipe though. You must have something wrong, because my truck will do 24psi and can get the pyro honkin and I am very close to stock (1/2 turn on fuel and 1/2 turn on smoke screw). See my sig for the rest.

Travis. .

 

[sparks57]

Another sure fire sign of a failing pump is your truck won't shutoff when you turn off the key. Mine did it.



You'll also notice the pump sounds kinda squishy, not sharp and snappy like new pumps.

 

[DanaLittle]

Egt probe is in the manifold. The truck starts on the first revolution and shut down fine. I guess i will just run it as is until i can afford some new injectors and a turbo upgrade. Thanks for the replies Dana

 

[dpuckett]

Double check the pyrometer connections. 24psi sounds a little low for maxed out settings, but if you are getting enough fuel for 24psi, you should see more than 350deg. Heck, sometimes, I cant get below 350 for a minute or more. How is your throttle response? I mean, in low gear, do you have to move the pedal much to get, say, 75% of your RPMs? That can be something with your advance wearing down. Pump shop said that was what was wrong with my pump, and I noticed a big difference later. I know it is kinda hard to explain, but you should get quite a bit of RPM from little pedal movement, kind of like bobtailing with an old NTC350 Cummins- hit the governor at 1/2 throttle.



I'd say it the 19mpg is a hair low, but driving habits can make a 2-3mpg difference, and you do have an auto, so it may be in line.



Daniel

 

[sparks57]

Good point, definately check your timing... retarded timing can cause major power losses. Over time, the torque on the injection pump can cause it to work it's way away from the block, causing retarded timing.



Does your truck smoke white a lot? Especially when cold?

 

[DanaLittle]

throttle response is real good and the truck has just a little bit of white smoke only when its cold out. I,ll have to check the timing haven't done that yet. I'll double check the pyro connections. Could the pyro gauge be bad?

 

[sparks57]

Anything mechanical or electrical can fail!

 

[JTCash]

Who is JLeonard

& how do I contact him?



Thanks,



R/

Jim

 

[1stgen4evr]

J is a member and you can PM. (private message) He is a regular on the first gen posts. You can probably find him in one of the current postings. But you can also find him on the member list. If you see his forum handle on a post, click on that and it will open to a page from which you can PM. The manual is a large document and will be a large download. If you are on a slow modum, it will be slow to download.



James



edit: sent you a PM. Click on the flashing banner and it will go to the PM page.

 

[JTCash]

Many thanks

Thanks guys... James is right, I'm new, but I'm learning.



Respectfully,



Jim