Engine Bogs Out in 3rd Gear

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Mar 9, 2013 | 07:28 PM

jhuffman

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Engine Bogs Out in 3rd Gear

Hi,

My Dad has an 87 Chinook (mini camper on e350 frame) with a 460 and a 3 speed automatic transmission. Last year it ran great. He stored it for 5-6 months with a full tank of gas. Now it bogs out only in 3rd gear. In 1st and 2nd gear it runs great, lots of power. At about 40-45 MPH when driving normally, it will bog out, but not die. If he slows down it runs fine. He can also leave it in Park and rev the engine up without a problem, and he can manually put it in 1st gear and or 2nd gear and it runs great at all RPMS. The problem appears to be related to 3rd gear (or possibly 40-45MPH)?

If anyone has any suggestions, we would greatly appreciate it.

Thanks!

Jonathan Huffman

Mar 9, 2013 | 09:03 PM

Beechkid

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Could be several items...but what initailly comes to my mind is without a fuel stabilizer, varnish has formed around some of the carb parts so to speak....with fresh gas, fuel stabilizer and use, it will be ok, partially loked fuel line/filter.......the other immediate & assuming it has a mechanical fuel pump, pin holes can dveelope in the fuel pump diaphram....the engine runs fine @ idle, low speed but with a load it runs out of gas at the upper end, eventually is gets worse at the lower rpm's.

Mar 9, 2013 | 10:42 PM

jhuffman

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Thanks for the response. The fuel pump is electric in the tank. I don't think stabilizer was used prior to storage, but I'm not certain. It seems to be such an odd problem since it runs so well in the lower gears even at high RPM. It's not until the transmission shifts to 3rd that the problem exists. It seems as though damage from old fuel would affect the engine similarly across all gears. Of course neither of us are mechanics per say, so maybe we are missing something...like when is the engine under the heaviest load? My thought is that it would be at the start of acceleration from a dead stop.

Maybe we should consider siphoning the tank and refilling with fresh fuel?

Thanks again,

Jonathan