Help me get it running again? (1 Viewer)

[Nemesis Gnat]

Hey guys,

It's been a little while since I've posted, and it's been almost as long since my 60 has been my daily driver. Long story short, I bought a 95 Cummins, it burned down in a forest fire, and now I gotta get the cruiser running again before the snow hits.

It is already low on compression on number 2. It leaks out the exhaust valve. That will be dealt with as soon as funds permit... It started and ran reliably even after that problem developed. Since then it started to stumble and die intermittently and got harder and harder to start as the days went on.

So I bought a carb rebuild kit. It needed it bad, my secondary diaphragm looked like a folded umbrella, my primary throttle body was black as night... Got it back together, reinstalled the carb, still no start, noticed that the float bowl wasn't filling. Weak stream coming from the fuel pump. Put a new fuel pump on. Float bowl filled. It started right up, but it ran rough and wouldn't restart when I let it stumble to death.

That there is my question... What's going on?

It looks like it may be leaking fuel slightly from the slow cut valve, but that may also be from the fuel line pressure test. The boot is broken regardless, so it should be replaced according to the FSM.

Would a bad slow cut valve cause a no start/rough run issue?

Sorry for the essay and thanks in advance for any help. It already feels good to be back in the cruiser world...

 

[riverguide]

It starts right up with or without a few pumps of the pedal? After it stumbles it won't start up right away...how long do you have to wait until it starts back up?

 

[Nemesis Gnat]

Sorry for the delay in response. Busy busy busy...

Anyways, if I let it sit for a while, it starts right back up again. My starting routine is whatever happens to get it running at the time, but more often than not the factory suggested combination of pedal pumps and choke positions does the trick. After I let it sit, when it fires up again, it runs great for about a minute, then starts to run rough again, then stumbles to death.

That would seem to indicate to me that it is getting fuel from somewhere that is richening it to the point that it dies, then, after letting some fuel evaporate, it is happy again... Agree? Disagree?

Also, my slow cut valve is sure enough leaking (at least exteriorly). Any thoughts on the effect that would have?


I will say this though: For that minute that it runs well before it starts to stumble again, it's sweeeeet. I can't wait to take it out for a proper drive. Everyone should rebuild their carb right now.

 

[Nemesis Gnat]

Well I've done some more research and more tinkering and this is what I have to report.

I looked into the slow cut valve... Turns out I'm not the only one that has had a leak. Looks like it doesn't give the symptoms I have. It will be gutted and plugged up to eliminate the leak.

I've tried tinkering with the idle mixture screw (It was 4.5 turns from closed, what is a good rough starting point? I live just below 8000ft if it matters.), adjusting the idle screw, and checking/ grounding the ICS, all to no avail. It has begun to randomly start easily, but most of the time it is still very hard to start. Still very inconsistent below 1000 rpms or so, and still no idle. It has also started to forcefully spit back out of the carb when it is started cold...

I'm freakin' stumped

Anybody?

 

[riverguide]

I know this sounds stupid but I just bought my cruiser this past spring and after a month or so of owning it it started having some starting issues. So I changed the alternator and the battery cables, got a new battery, checked a lot of items...

I said screw it and decided to take it fishing. I was sitting in the parking lot of the fishing area and I went to move the truck and it wouldn't start. So of course this old man comes over and says, OPEN THE HOOD AND GET ME TO THE CARB. I was thinking oh geez...well long story short he ended up being an old carb mechanic and we played around with it for maybe 2 or 3 minutes. What was the problem??? I was pumping too much gas and was flooding it so I would have to let it sit...then it would start. Haven't had the problem since...

Not saying that is the issue but it could be.

In this cold weather we are having I am having a harder time starting it and it is stumbling afterwards. I do take that as a fuel delivering issue and am looking at my carb for problems(it;s never been rebuilt).
Otherwise it could be as simple as too much or not enough fuel, perhaps caused by you.

 

[GLTHFJ60]

Aside from fuel, have you had a vacuum gauge on the manifold yet?

 

[FJ40Jim]

Ignore the slow cut valve for now. it is not a problem.

When it dies, where is the fuel level on the sight glass?

When it is hard to start, take the lid off the aircleaner and look in the throat of the carb. Grab the linkage and work the throttle. The accel pump should produce a nice stream of gas in the primary barrel, the AP rocker arm on top of the carb should be observed to move in unison w/ the throttle linkage.

What is the vehicle's smog status? Desmogged? Smog equipment still present, but unknown condition? Is vehicle smog tested annually?

 

[mwebfj60]

I recently had the same problem after a carb rebuild/fuel pump replacement. Mine ran fine for a couple of days and then it would die out and fuel would be running out of the slow cut valve. Mine ended up being a little sliver of what looked like grey plastic lodged inside the float valve. This was keeping the valve open and completely flooding the carb (causing fuel to leak out the slow cut) and causing the motor to die out. I am pretty sure it came from the new fuel pump. It only took a couple of minutes to take the top of the carb back off and find it. Also, I could see through the site glass that my bowl was completely full. Good Luck.

 

[Nemesis Gnat]

Sorry again for the delayed response! I've got a whole list of excuses if you wanna hear them! Anyways...

Everything is desmogged and vacuum lines are routed as per the desmog diagram on this site. It's been desmogged for a while so I don't think the problem is there.

The fuel level in the float bowl is always just about perfect, maybe slightly high... Is the needle valve worth double checking? I don't see any overflow into the throttle body, but if there were some, would it cause this condition?

When I cycle the linkage, I get a very healthy stream of fuel from the accelerator pump.

I have not checked it with a vacuum gauge for two reasons. First, my vacuum gauge melted in the same forest fire that destroyed my Dodge and I haven't replaced it yet. Second, with the gimpy cylinder, I expect my vacuum reading to be less than optimal. Could the vacuum be bad enough that it causes this problem?

I got it running long enough to take it down the street and back. It is backfiring a LOT when I engine brake... It also, when hot, will sometimes idle at about 1000-1200 rpms but then stumble and die other times.


I think my current plan of attack is to just go ahead and try to move forward with the valve job as quickly as money allows... Knock off the problems I know about to try to simplify the situation.

I appreciate the help so far!