throttle floating, at high rpm's... is it the pump

[kane66]

Last week I installed a engine and tried "starting" the engine against the valves. Anyway when I finally got it started it would idle but if I gave it any fuel it would float at high rpms and then come down to a rough idle and die. I figured it was the valves, but after some good advice on this board I went back to it. Well this week I got back on it and properly set the timing on the pump. It's still doing the same thing.It also smokes gray really bad on start up and when it warms up it still smokes gray but not as bad.

    This is the pump that I got "rebuilt from Prothe" and I thought that the local shop had finally got it working right as I was able to go 100 miles on it no problem, but could the stress of the engine swap caused it to go all wonky again. Can anyone think of something else that could cause it to "float" like that. Any help appreciated as I again I will have a week to figure this out before I can check it out.

[jtanguay]

are the rpm's hanging?

[vanbcguy]

Hmm... Everything ruled out wrt the valve train?  A damaged lifter could do some weird things for sure...

Your pump could definitely be causing problems though... Do you know what the shop did to get it behaving in the first place?  Have you tried anything to "unstick" the internals of the pump like running it off a bottle of ATF or diesel purge?

[veedubcanuck]

Faulty injectors could cause it to happen too.

[AudiVWguy]

I hate to say this but I also got a pump back from Prothe that wouldn't work. I had a known good pump and swapped in. Started and ran perfect. About a year later I saved up enough to get a Giles SuperPump. Do you have one you can swap?

[kane66]

jtanguay. the rpms do hang, even though the throttle is were it was idling just a moment before, then it drops off to a rough idle, then dies.

vanbcguy: unfortunately I don't know enough about the internal workings of the pump to know what is going on, or what the shop did. All they told me is that they calibrated it and changed some springs.

veedubcanuck: I have a hard time believing that the injectors went bad in 24 hours since I drove it up with no problems the day before. of course anything is possible

AudiVWguy: I've spoken my piece about Prothe and defiantly dont want to turn this into a flame thread, but I do have a good pump on the way. I was almost tempted to pull the pump out of my running car just to rule out the pump but ran out of time before I got that desperate.

thanks for all the suggestions keep them coming I would like to have as much info as I can before I work on the car again.

[jtanguay]

if the rpm's are hanging the pump just needs to be tweaked.  its sometimes hard to calibrate a pump and get it to run perfectly without adjustment on a car that is out of spec.  i'd say 1/4 turn out of the fuel screw will probably fix the issue.

[kane66]

I will be both relieved and aggravated if I did all that work and all I had to do was adjust a stupid screw

[fatmobile]

Yep, not sure why it is smoking grey,...
 but too much fuel on the max fuel screw will cause RPMs to hang.
 Sticky springs on top of the pump will do the same.

[kane66]

so I tried turning out the fuel screw and I couldn't seem to dial it in :x  :x  :x. I tried the 1/4 turn out didn't help. So I kept trying small adjustments an it would either idle fine but give it a little fuel and it would  rev up to high rpms. Or I would turn it so far that it would idle so rough it would eventually die. I don't know I think I'm going to pull the pump off the running car and swap them to see if that makes the difference.  


why do I have so much trouble with fuel pumps.

[fatmobile]

Adjust the idle as you turn the screw.
 Idle will drop when you turn it out.