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32dmadden, Auto Repair Shop Owner
Category: Ford
Satisfied Customers: 1207
Experience:  A.S.E. Certified Master Technician, L-1 37 yrs. Auto Repair Experience
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Ford E-350 Super Duty 1989 ford 460 motorhome runs great when

Resolved Question:

1989 ford 460 motorhome runs great when you start out on a trip. when you make the first stop, and take off again, the engine will not have any top end, in. it has a 3 speed trans, to pick up speed have to drop it in to 2nd. pull off freeway, put in nuetral it revs up fine, back to drive falls on it face.--this happens when outside temp is in the 100's, i have changed two fuel pumps, fuel filters,diafram fuel moduel, checked fuel pressure.-- thought it could be trans do to a sensor, it fills as the motorhome goes into a limp mode. when you hit cooler temps or it sits over night runs fine again. should fuel rails have heat shields on them to protect from heat? also no check engine ever comes on.
Submitted: 6 years ago.
Category: Ford
Expert:  32dmadden replied 6 years ago.

Check to see if the exhaust is stopped up. You can do this with a vacuum gauge. Get the vehicle up to temp and put a load on the engine. Snap the throttle wide open. The vacuum should drop and then start climbing almost immediately. If it stays very low the exhaust is stopped up. Let me know what you find and we can go from there.


Customer: replied 6 years ago.
checking exhaust vacuum sould be done at normal running or when engine problem happens. where do i check vacuum, manifold or exhaust side
Expert:  32dmadden replied 6 years ago.
Should be checked when problem is happening. Check the vacuum at the intake manifold. There should be a vacuum tee on the intake that you can use.
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