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Crusader 8.1 MPI fuel pressure drop

C

captainjimmy

New member
I have 8.1 MPI engines in my 2003 Tiara 29 Coronet, 400 hours on both. Port engine loses RPM slowly after cruising at 15 - 20 min, no codes, no issues noted on gauges. After shutting down and restarting, again runs for a while before issue repeats. Mechanics to date have replaced fuel filter elements, replaced fuel filter discs, replaced high and low-pressure fuel pumps, checked fuel shutoff valves at tank (anti-siphon), and checked fuel lifter tubes to single tank. Fuel chllers also check out. Pressure testing at fuel rail shows that fuel pressure drops from 45 to 25 when this occurs. They feel they have ruled out flow restriction upstrean of engine. Mechanics are now at a loss of what to do next. Has anyone seen this? Can it be some faulty information from a sensor coming to the fuel pump? Any other ideas? Season is almost over and I'd like to get it fixed before winter storage (Ohio / Lake Erie).
 
Anyone check the fuel tank vent?
Run until it stops than go to the gas cap and open it while listening close for air being sucked in
 
Not real familiar with Crusader but noting fuel pressure drops, this is where I would focus

Pressure testing at fuel rail shows that fuel pressure drops from 45 to 25 when this occurs.
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Fuel pumps are new and hopefully OEM and not after market, then regulator is next item. The Reg is a mechanical item and either it works according to spec or it doesn't, no middle ground. If pumps are producing sufficient pressure (in excess of need) than the Reg just reduces pressure to spec.

To determine if HP pump can produce more than 45 psi the supply needs to be blocked off and see if it can produce 60 or more psi. Do not due this with Reg attached because that much pressure can damage it, do it on a bench.

The Reg can be tested on the bench using compressed air and air pressure regulator. Apply air below 30 psi and slowly increase until it opens and releases air, note spec
 
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