AAZ pump and running problem

[dontdoemyourself]

After reading the "how to make your 1.9td a faster car" I attempted to make my AAZ in my Vanagon go up passes with less struggle. Long story short, I've been having a lot of trouble with cold starts, where the engine will start and idle just fine, but as soon as I give it gas it wants to shudder and die. Now on to what's been fixed on the engine since I've owned it.. Sent pump to prothe to be rebuilt because of a leaking cold start assembly o-ring, which they didn't fix, damnit. So, I tore it back apart, replaced the t belt, set timing to .93mm and fixed the leak. Everything was good until a few weeks back when I set my timing back to .83mm,  I noticed starts getting harder and a little less power.. Typical for retarding the timing a bit,  but what I wasn't expecting was the stalling.. It seems like when it was cold, with the cold start lever pulled out, it would stall if I have it any gas. From there I tried to increase my cold idle, which didn't help. So, I put my fuel screw back to what seemed to be the stock setting, basing that off of my tamper collar, now it won't run at all.. Tonight I'm going to check my crank to cam timing and go from there.. Sorry for the story book here, but has anyone tweaked there pump too much and had this problem before? Thanks in advance for any help!
-Tyler

[theman53]

If you messed with the fuel screw then put it back to where it was. If it started and you then turned it down and now it won't logic says turn it back up. IIRC the top range for the aaz was around .93 so I would stick to that. .83 will have diminished gains on the low end and if compression is down it may cause harder starting. Also, if the thing ran at all with Prothe pump consider yourself lucky. Many have had a no run situation with his stuff from the very beginning. You may just have to have the pump rebuilt by someone who knows how.

[dontdoemyourself]

I am considering having the pump rebuilt by Giles, which I should have done in the first place.. although rebuilding my DK trans should be higher on the list in order to lower cruising rpms.. Anyone have an idea how far booked out Giles is? I will call when I have money saved up, until then I'd like to do a few other small mods (1.6td boost pin, passat 1.8t inter cooler, external oil cooler, other ideas ??) have egt probe on the way, tach, boost gauge, oil pressure and temp to install. I will readjust my timing tomorrow and see how it responds and give an update. Thanks !

[burn_your_money]

Sounds like you have air in the fuel. Do you have clear lines to check this?

[dontdoemyourself]

I don't have clear lines, would napa have them?  My pump has started to leak from the cold start mechanism again, so that would make a lot of sense..  I replaced the o ring myself with a seal I got from the hardware store, seems like it wasn't meant for diesel..

[dontdoemyourself]

Ok, little update.. Put clear fuel lines on, bubbles in the return line apparent. When i give it throttle bubbles get worse, then when I let off the throttle bubbles seem to go through the pump back into the feed line. What should be my next test?

[TylerDurden]

I'd bottle-feed using known good lines and check that the inlet banjo fitting is tight.

If the banjo fitting is ok, it may just be the mainshaft seal, a $20 buck part anyone can replace. However, the main seal can leak from age, or from a worn mainshaft bushing, so I'd wiggle the mainshaft and consider a rebuild if the play is more than a millimeter.

[dontdoemyourself]

Thanks, if it needs a rebuild I'm sending it to Giles.. I'll do the bottle feed and banjo bolt tests, and check main shaft play first though. The o-ring for my cold start lever needs replacing as well so if the main shaft seal is blown it won't be much more effort.

[vanbcguy]

If you have multiple leaking seals then the whole pump should be done. Otherwise you're just playing whack a mole  till you've eventually gone through them all.

[dontdoemyourself]

Got it, I told myself I was going to do some head porting and studs if I had to tear into the engine again, opening the can of worms.

[dontdoemyourself]

So, some updates.. Tore pump off, replaced leaking cold start lever seals, checked main shaft play, seemed totally within spec,  barely moved and the seal appeared to be in good shape. Reset timing to .95mm, and broke the banjo bolt for my turbo oil feed line over tightening it.. D'oh! I'm sure a cis fuel fitting one is close to the same thing... Then i can see if the leak was causing my problem. I'm going to bottle feed it, but Is there any chance my fuel return lines or tank venting system could be malfunctioning ? Not sure of how to test that one..

[dontdoemyourself]

Well, everything seems to be back to normal, maybe I can get around to some mods. No air in the fuel, has the same power it used to. What source is everyone using for clear lines? Found some that worked , but they are soft PVC and don't seem the same type of plastic as I've seen on other diesels.

[burn_your_money]

I think people use tygon lines. The PVC will turn rock hard and leak on you eventually. You can browse mcmastercarr to see what is available that is compatible with diesel.

[dontdoemyourself]

Thanks, switched to the tygon ones and they seem tougher than the crappy vinyl ones I was using, no more leaks or air in lines.. I'm having trouble with cold starts though.. Could timing be a bit too far advanced @ .95mm? I'll turn it back to .87-.89mm and test. Could fuel screw may be turned in too far? Also, turning my idle adjust screw doesn't seem to do much to raise or lower it.. What could cause that?

[burn_your_money]

Sounds like a glowplug issue. 95 is near perfect for AAZs.

Are you sure you're turning the idle screw and not the residual fuel screw?