I have a 1994 winnebago 27 foot brave class a motorhome with a 454 motor and 40000 kms on it. When i climb a hill in hot weather it all of a sudden dies and when i try to restart it after it sits for a while it surges with the rpms rising and falling about 500 rpms. After continuing on down the road after about 30 mins it seems fine untill all of a sudden it does it again, i lose brakes and power steering and it is quite unnerving.It happens when the weather is hotter out and when climbing hills. any help would be appreciated.
Most vehicles with fuel injection will not get vapor lock, because the fuel pressure is supposed to be about 70 PSI from the tank to the engine fuel injectors, and the fuel is not supposed to boil at that pressure. However what you described is vapor lock.
You could be using fuel with a winter blend, that is designed to boil at a lower temperature, or to much alcohol, or is poor quality (BP). You might also have a blocked fuel filter.
I would start by installing a new fuel filter.
Change fuel suppliers to Chevron or Mobil. See if that improves the situation.
If that does not work, find someplace that can check your fuel pressure at highway speeds, or just remove the fuel tank and put in a new fuel pump.
This is assuming that you have done the usual checks, loosen the fuel cap when the engine stalls to see if the tank is pressurized or in a vacuum.
The reason you lose brakes is the power steering pump also runs the power brake booster. Yea, it is no fun to happen suddenly, at least it is the uphill, not the downgrade! That would get exciting quickly! If you are in neutral, you should have some power steering and braking while cranking over the engine. But don't run the starter motor more than 30 seconds at a time.
This is something you really want to fix before your next trip through the mountains in the summertime!
Could be your air filter is satuated with water, replace it if so.It will also do that if it over heats, so check coolant level, when it's cold. One other problem could be a bad oil presure sensor, as on these units it shuts off fuel pump if oil presure is low. That would be making your oil presure guage go very high and then very low at the same time the fuel cuts off.
Your 454 probably has a carburetor. I once had similar issues which was caused by a failing gasket on the carburetor. Under load it was sucking in air and causing problems. A mechanic used some type of spray around the base of the carburetor to identify the problem.
When it happens again- check and see if there is spark from the ignition. If there isn't any, it is then ignition related, which is more likely your problem.
Skip
1996 32' Monaco Windsor DP
Cummins 5.9L 230+ HP
5 Airbags in front- 4 in back
A 94 will have TBI. Last carb was about 89. The fuel pump is in the tank.
The surging could indicate fuel starvation.
When was the last time the filter was replaced?
I would replace the filter first. Then, if no help, connect a fuel pressure gauge and watch it is the problem occurs. If you have low pressure coincident with the problem, it is likely the filter or the sock. Either way, the tank has to come down, so use it up or have somewhere else to store it or use it so you don't end up needing to drop a full tank.
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