FUEL PROBLEM HELP??

rebelron2

rebelron2

New member
My freshly rebuilt 345 is giving me fits. I put a new Holley Street Avenger 2 barrel on it and it will run fine at first, but after you go somewhere and turn it off, when you get back on the road, it will start cutting out when you get to 3rd gear. It will actually shut off and coast for a short time, less than a minute, and then sputter and start back up. We've dropped the tank, cleaned it out and replaced the pickup tube and sending unit, replaced the fuel cap, installed an Edelbrock electric fuel pump and regulator, (set to 6 psi), new fuel filters, new heat shield carb gasket...... I really don't know what the issue is. Yesterday I took it to the farm and when I headed home, it did not want to start, almost like it was flooded. I held the accelerator to the floor to get it to start. It has a new ignition system also. Has anyone else had this problem with their Scout? (Mine is a 79 Scout II, but the 345 is out of a 1973 truck). I want to check everything. I am looking at a 4 barrel aluminum intake and Edelbrock carb, but I hate to drop the money in that and still have the issue. Any help would be much appreciated. Thanks!
 
Is the carb a 500 or 350 cfm version? Please provide more specifics about your ignition setup. This is sounding a little like vapor lock, but the lektrik pump should be able to overcome that.
 
Thanks for your response. It is the 500 cfm. I am running the Holley distributor that was on the 345, but replaced the points with a Pertronix module and matching coil.
 

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That carb probably isn't your overriding issue, but it isn't helping matters either. It's too much carb for the engine across the spectrum. Are you using the '79 wiring harness in it's entirety? A '79 model would have most likely had a Prestolite electronic ignition originally. Then you swapped in an engine from an older vehicle with a points distributor. Did you ever run it with the points, including a resistor wire or ballast resistor? Now that it has an eliminator module, I'm just want to make sure that the wiring to the coil and distributor is correct.
 
No, The engine was not running when I got it. After the rebuild, I have only run it with the current system. Yes, it has the original wiring from 1979. IH Parts sold me everything for the distributor to match.
 
Ok. I'm curious about your fuel pump location. Were there any installation instructions with it? I'm surprised you don't have it located closer to the fuel tank.
 
I wanted to mount it closer to the tank, they do better pushing than pulling, but it has a homemade aluminum fuel tank and it left me with nowhere to mount it near the tank.
 
Yeah, I thought so. Hmm. Well, nothing aside from your carb model and fuel pump location jump out at me as being problematic. The thing with fuel is, when it gets hot it begins to change from a liquid to a vapor. It's much more difficult to move when that happens. Turning a pusher pump into a puller might work as long as the fuel stays cool, but maybe not so much when it gets hot. If it were me, I'd have another look with some outside the box thinking about how I might relocate that pump closer to the tank. The next time it dies on you when there's plenty of engine heat, pop the hood and look down into the carb as you blip the throttle. If you don't see two strong streams, it's likely because your fuel has vaporized between the fuel pump and the carb. Almost as if you're out of gas even when you know you have plenty in the tank.
 
Okay, that sounds like a plan. I'll figure out a way to get the pump back at the tank. Would the aluminum intake and a 600 cfm Edelbrock help?
Thanks again, Ron
 
If you disconnect the fuel line at the carb and put the end in a can, how much fuel do you get with the pump on for about 15 sec? Also how is your tank vented?
 
The tank is vented and I put a vented locking gas cap on it. I'll have to wait for it to cool down because I just drove it. One thing I just noticed though, the fuel in the sight glass on the side of the carb is bubbling.
 
I think you'd be having the same issue. You need to fix the root problem first. Get your pump pushing instead of pulling and insulate your fuel lines from direct heat exposure, especially if any portion of the line is metal and near the exhaust manifold.
 
Do you have a good insulated carb base gasket installed? Can't see from your photo.
The Holley p/n 108-52 is recommended for the IH SV-8 engines.
It insulates the carb and deflects radiant heat away from the fuel bowl.

Holley p:n 108-52 Base Gasket-2.jpg

1. I'm curious as to the reason for the electric fuel pump when the mechanical fuel pump is quite sufficient and provides the correct fuel pressure and flow for any carb utilized. Electric fuel pumps tend to provide higher pressures and can overpower the needle & seat and overfill the carb, ie. flooding etc.
2. What is the source of the 12VDC for the electric choke........and
3. I see several leads attached to the coil + terminal. What are they? Typically the coil + only needs one or two leads there, depending on the ignition system utilized and how that system is wired.
4. There are other issues caused by the aftermarket air filter housing, but those can be addressed later, if you wish.
 
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is your home made tank still mounted in the same position as the factory tank ?

Yes, it is, but it is larger than the original.
 
Do you have a good insulated carb base gasket installed? Can't see from your photo.
The Holley p/n 108-52 is recommended for the IH SV-8 engines.
It insulates the carb and deflects radiant heat away from the fuel bowl.

I have a heat shield gasket that I purchased from ihparts, it is similar to the one in the picture, but it offset and doesn't shield the entire float bowl.


1. I'm curious as to the reason for the electric fuel pump when the mechanical fuel pump is quite sufficient and provides the correct fuel pressure and flow for any carb utilized. Electric fuel pumps tend to provide higher pressures and can overpower the needle & seat and overfill the carb, ie. flooding etc.

The problem was there with the mechanical pump. I switched to the electric pump hoping to fix it, it did get better.

2. What is the source of the 12VDC for the electric choke........and

An ignition plug in the fuse box.

3. I see several leads attached to the coil + terminal. What are they? Typically the coil + only needs one or two leads there, depending on the ignition system utilized and how that system is wired.

The electric fuel pump hot wire.

4. There are other issues caused by the aftermarket air filter housing, but those can be addressed later, if you wish.

There is just enough room for the small air cleaner, otherwise the hood will not close.
 
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