idles, but won't rev...

[makya]

I'm trying to get the dually working, and I have the motor from the 4x in it.

 

It will idle, and it starts to rev up from the accel. pump shooting fuel, but after that it won't run unless I keep it floored, & then it will sputter at about 1200 rpms and die as soon as I let off.

 

The bowl is staying 1/2 full at the sight glass, There's no water in the fuel, timings good. If i cover the carb with my hand it will rev up, but it sucking so much fuel it will actually splash my hand a little:blink: I adjusted the air/fuel mixture but it didn't help, so I put it back to 2-1/2 turns out.

 

any one got an idea? I could use some help.

[tiltnose510]

It sounds like there is possibly a very large vacuum leak. First thought was timing but you are saying that it is right. If you are choking it and it's revving... What else can it be? (in honest thought here-not mocking) Check all the vacuum lines or cap most of them to test what they're conected to.The brake booster is probably the biggest possibility for a leak that will do what you're describing so you may want to take it out of the equation for a moment. Just some thoughts without actually being there.

Mark

[makya]

yeah, it's a 78 so its got a ton of smog on it. I haven't replaced all of the old lines so I probably have cracks in them.(this truck sat for almost ten years before I found it.), thanks.

 

If it wasn't for california, I wouldn't have all the smog on it. but I don't have a choice.

[tiltnose510]

Good excuse for fuel injection.

[datzenmike]

Primary jet plugged.

It can be got at with difficulty with carb on, but better off. There are a pair of brass plugs under the sight glass at the front of the carb. The one closest to the valve cover side covers the access to the primary jet. Empty the fuel out and remove the 10mm plug. Up inside, is the jet. Using a proper size flat screwdriver, remove and check the orifice. It probably has a speck of dirt blocking it and prevents fuel from feeding the primary circuit. It idles because fuel for idle is supplied through a separate circuit.

 

It might be a good idea to clean the whole carb if you have it off. Rebuild kits are reasonable and there are instructions and a gauge for setting float drop and the choke unloader.

 

Replace the in line filter now and at least every year ($5) I do mine twice a year. Cut the old one open and examine the sediment.

[banzai510(hainz)]

try adj the timming. That id someone fucked with the oil pump dist drive. Those are system of a distributor off a tooth also.

 

But yea Im thinking primary jet also. One way to eliminate this is put your hand over the main barrel and stick a screw driver in the second barrel to keep it running. and see if that side works. It will pull gas from the second main jet

[makya]

thanks guys, I need to rebuild the carb anyway. I doubt it's the timing just because it ran when it was in the 4x and I haven't touched it since.

 

I'll update with results for future reference.

[makya]

So I pulled the carb. and pulled the jets. they were clean popped open the front of the bowl and it was clean inside also, so I gave it a quick once over with some carb cleaner and plugged off all the vacuum lines and it ran!

 

I need to go through and hook up the lines again(with new rubber), but I got to drive it around the block a few times!

 

WOOOHOO! :) the DUALLY LIVES!!

[]2eDeYe]

PIC'S! :fu:

[ramseys21]

pics! haha