IH 300U fuel system problems

M Sailer · Oct 23, 2009

I have a 56' IH 300U, I just bought it and It ran well for a few hours then lost power, sputtered, and sometime quit. It had sat for many years before, so I cleaned out the tank, line, carb, and bulb. Nothing worked. It's not Electrical though. I notice a slight leak off the fuel vacuum (not sure of the actual term) It seems to be starved of gas at higher RPM or when a load is put on the engine, or at any random time it will sputter and die. I don't think it's the carb. Any suggestions?

Mike (WA) · Oct 23, 2009

Can you make it run better by pulling out the choke when it sputters? If so, its a sign of either plugged fuel path somewhere (more likely) or a vacuum leak (less likely).

M Sailer · Oct 23, 2009

I have checked all possible plugged paths, other than a vacuum issue. How would I figure out if the vacuum is the issue? Also, It is amazing how little power it has even when it isn't sputtering.

Thanks for the reply!

old · Oct 23, 2009

Well I would start by pulling the drain plug out of the bottom of the carb and make sure you have a good steady flow of gas there. Now as for you saying it is not an electrical problem how do you know that?? Do you have a good blue/white spark that will jump a 1/4 inch gap??? Also what is the compression in each cylinder. From what you have said it could be a number of problems and since you say low power it sound like low compression and or spark and or timing etc etc

Adrian · Oct 23, 2009

Just finished plowing with a 300u pulling 3-14 s. Had the same problem with poor operation under load. Unscrew the sediment bowl from the gas tank and drain it. Take a quart of gas and dump it in the tank to rinse the tank out. Check your sediment bowl going into the tank ,blow it out with air and make sure it is open and clean. Worked for me! I also put a gas filter inline before the carberator. Good Luck
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rustyfarmall · Oct 23, 2009

Old is correct. Fuel problems will often mimic electrical/ignition problems, and ignition problems will often mimic fuel problems. The next time it just stops running, get off and lay your hand on the ignition coil. If it it HOT, or at least extremely warm, you have found the culprit. If the coil seems fine, then slowly remove the fuel tank cap and listen for a sucking noise. Sometimes the tiny little vent holes in those caps gets plugged, which creates a vaccuum in the gas tank, and the result is no fuel getting to the carburetor. A 300 U is relatively simple to work on, try to not over anaylize the running problems.

sd pete · Oct 23, 2009

Did you pull the screen out of the Carb. inlet?

M Sailer · Oct 23, 2009

Thanks Guys!
I"ll give your suggestions a try. And Yes, I may be looking past a more obvious solution.

I let you know what happens.

Thanks!

Mike (WA) · Oct 23, 2009

Trick for checking a vacuum leak is to spray something flammable (WD 40 is good, I'd stay away from ether!) around the base of the intake manifold (not where it can go into the carb intake) and see if it smoothes out or gains RPM momentarily. Good way to diagnose leaking intake manifold gasket, when you can't see it.

IH 300U fuel system problems

M Sailer

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Mike (WA)

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M Sailer

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old

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Adrian

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sd pete

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