Sputter (and sometimes dies)

[cowain]

I recently got an 85 K-5 with the 305 V-8 and quadrajet. The beast is awesome and I've been enjoying the hell out of it and I'm slowly working on various items I want to fix/upgrade.

However, the one thing that has to go ASAP is this G.D. sputter, so I hope the board can help me troubleshoot it. Periodically (it seems to be random) under acceleration the truck will sputter and occasionally die. It doesn't seem to be linked to any RPM range or uphill/downhill, etc. The first few times it did this we were able to fire it right back up but most recently it died (on a moderate incline) and I couldn't get it restarted. We left it, went to dinner, and then it fired right up. On the way home it died multiple times but we got it all the way home. The sputter seems to be a rich condition but the way home seemed to be a starvation issue (kind of - sometimes putting it in N and keeping revs up worked, sometimes it didn't).

It has a recently replaced cap and rotor as well as plugs and wires. I've done some searching and someone with something similar had the problem resolved with a new ignition module. I also think it could be something to do with the carb. One last piece of info, the brakes seem somewhat squishy (or have a lot of pedal travel to them) and when I pump them repeatedly the engine starts running rough and the oil pressure drops from like 50 to like 30. Don't know if that has crap to do with anything though.

Thoughts? Where to start?

 

[Jason4x4]

check fuel filter, you will have to cut it open because it filters from the inside out, Check the brake booster, It could be sucking vacuum, and causing it also.

 

[Elevator Man]

Mine does that sometimes also, seems to do it only when it's really hot. I think the gas might be getting to hot and boiling. Post up some pics of your rig. Nice to see some on from Central AR I'm not to far from ya maybe we could wheel some time!

 

[cowain]

check fuel filter, you will have to cut it open because it filters from the inside out, Check the brake booster, It could be sucking vacuum, and causing it also.

What should I be looking for on the brake booster? Checking the vacuum or what?

 

[cowain]

Mine does that sometimes also, seems to do it only when it's really hot. I think the gas might be getting to hot and boiling. Post up some pics of your rig. Nice to see some on from Central AR I'm not to far from ya maybe we could wheel some time!

Good point - it was hotter than hell on the day it was having all sorts of problems. Only problem though is that it was still having problems on the way home after dinner and the temp. wasn't as bad then.

I do need to get some pics of the rig up here, but the wife has the camera in her car and she's at work.

I'll definitely be down to do a little wheelin some time once I get this bad boy up and running right.

 

[cowain]

Anyone else? Thoughts?

 

[k20]

Check the exhaust routing in relation to the fuel lines. Could be a new exhaust on it is causing vapor lock.

 

[cowain]

Check the exhaust routing in relation to the fuel lines. Could be a new exhaust on it is causing vapor lock.

Aha, I think this could be it. The guy before me had dual straight pipes put on it about 6 months ago. Upon further inspection, the passenger side pipe seems to run about 4 inches from the fuel lines the entire length of the frame.

What do I do to fix this (other than get a new exhaust done)? Wrap the whole exhaust pipe or spray it with hi temp paint or something?

 

[k20]

you could try fabbing a heat shield over the fuel lines, reroute the fuel lines outside the frame rail, or wrap the exhaust.