Interesting injector pump issue

[Dsl_Dog_Treat]

Was working on one of Darrins finds and thinking I was battling an air intrusion, I discovered yesterday that it may not be air but the IP itself.

After chasing down every possible air intrusion entry point, new return line kit, water separator cleaning, fuel filter replacing, ya know the drill.....
I think the problem FINALLY surfaced yesterday.

After trying to button up a few things I made one last attempt at trying to figure ou the problem with this 83 6.9 gremlin.

Fired it up and she did the normal surging like it still has air in it but it kept surgin all the way till the cold idle advance kicked off. As cool as it was yesterday morning, that was over 5 minutes of idling! :***:

Could it be that the advance piston is that worn to allow it to wander like that on a cold start up?

It's been driven and I couldn't detect any surging while the engine is under load tho.

 

[87crewdually]

Start it cold without the timing advance solinoid plugged in.

 

[phazertwo]

Start it cold without the timing advance solinoid plugged in.

X2

 

[Agnem]

Ron, the advance piston doesn't kick in until the RPM's get up far enough. However, if you can throw a timing meter on it, that would confirm if your problem is timing or not.

 

[Dsl_Dog_Treat]

A timing meter has been on my wish list for some time now and that reminds me to go see my Ford buddy to see if he's dug em out yet or found me anymore cool Rotunda tools.

This IP appears to be the original as I've got it advanced as far as I can rotate it to get the timing closer to the norm, but after allowing it to set for 36 hours and restarting with the advance disengaged, it's still surging...... CRAP!!!!

 

[Agnem]

Replace the normal inlet fitting with a brass nipple, and supply fuel to the pump with a piece of clear vinyl tubing coming from a gallon jug sitting on the air cleaner. No fuel pump is required for gravity feed in this test. That way you can determine once and for all if it is the pump or not.

 

[Brianedwardss]

^^^ Had to do this trick once, but it was on a 6.2L. Two weeks of no starts and re-looking over the fuel system finally forced me. After I got it started and ran in that configuration, I shut off the truck, and then arched the tubing so that any air would go from the pump to the top of the arch.. I left the truck and got lunch, came back and there were little tiny bubbles making there way up from the pump.

 

[SLC97SR5]

Ron, the advance piston doesn't kick in until the RPM's get up far enough. However, if you can throw a timing meter on it, that would confirm if your problem is timing or not.

When is the advance piston active? I thought as long as it had 12v it was kicking up the timing 2*.

BTW, I had this exact problem until I advanced my pump all the way to the passenger side. I have a wicked hot start issue and will soon be sending my DB2 to Mel to be Moosed.

To troubleshoot the timing being related to surging, when the Truck was warm I would run 12v to the advance solenoid, when I did this the surging was decreased.

 

[dyoung14]

I had a Ip that would "hunt for idle" driving at slow speeds was almost impossible because all the surging it would do, one day i cranked it and it was blowing white smoke, blew it all the way to town and back, and was running really bad, i pulled that ip and descoverd metal chunks inside the pump were it was comming apart

 

[Agnem]

When is the advance piston active? I thought as long as it had 12v it was kicking up the timing 2*.

BTW, I had this exact problem until I advanced my pump all the way to the passenger side. I have a wicked hot start issue and will soon be sending my DB2 to Mel to be Moosed.

To troubleshoot the timing being related to surging, when the Truck was warm I would run 12v to the advance solenoid, when I did this the surging was decreased.

Your talking about the cold idle advance which is a solenoid valve. I'm talking about the interaction between the slow speed advance (cam and arm on the side of the pump) and the advance piston (internal to the pump).

 

[DeepRoots]

on another note.....

Severely advanced timing will act like air in fuel. Same rough idle and "wanna run away with ya" treatment with throttle application (but it'd only do it sometime which made it hard to diagnose).

try retarding the timing just to rule it out.

Drew

 

[dyoung14]

on another note.....

Severely advanced timing will act like air in fuel. Same rough idle and "wanna run away with ya" treatment with throttle application (but it'd only do it sometime which made it hard to diagnose).

try retarding the timing just to rule it out.

Drew

WOW really? i never herd that

 

[Black dawg]

When is the advance piston active? I thought as long as it had 12v it was kicking up the timing 2*.

BTW, I had this exact problem until I advanced my pump all the way to the passenger side. I have a wicked hot start issue and will soon be sending my DB2 to Mel to be Moosed.

To troubleshoot the timing being related to surging, when the Truck was warm I would run 12v to the advance solenoid, when I did this the surging was decreased.[/QUOTE

the advance piston is pushed on by transfer pump pressure, the faster the pump is turned the more the timing is advanced, to a point. on the other end of the advance piston is housing pressure. when the cold advance sol is activated it reduces housing pressure to zero, letting the piston move in the advanced direction. the arm on the side of the pump bleeds off transfer pump pressure when pushed , by a servo valve inside the advance piston, retarding timing.