1995 Holiday Rambler Ford F53 460 acceleration issues
My motor home is a 30 foot Holiday Rambler on a 1995 Ford F53 chassis with a 460 engine. My particular issue is that it started initially to bog down excessively during hill climbs. Then after stopping at a light or stop sign, it would not accelerate from a stop. The more you tried accelerated, the worse it tried to go (last time from a stoplight, it backfired and the signal almost changed before we got through it being first in line). At times when fully warmed up, in park and rpm at about 4000, it will surge like the throttle position is changing. It seems to run fairly well on the highway. I have checked the TPS with an analog meter and the voltage is smooth and consistent throughout its travel. (almost 5v with throttle closed down to a bit less than 1v throttle open). The fuel pressure with pin 6 of the diagnostic connector shorted to ground and ignition on is between 37-38 psi. With the engine running at idle it is between 30-31psi. Pressure regulator disconnected from vacuum 37-38. WOT 37-38. These readings are consistent sitting still in park and while driving. The pressure never drops below 30 and never exceeds 38. I have checked the fuel pressure regulator (no fuel coming from the vacuum port with ignition on). New fuel filter (old one was easy to blow through and no junk came out). I used Seafoam spray cleaner in the air intake per instructions on the can (maybe a little difference). I have put 16 oz in the 75 gal tank (1/4 tank) and have put about 40 miles on it (a little improvement). I have checked the contacts on the fuel pump relay (clean and I can hear it operate). I cannot get to the connector on the pump to check the voltage without dropping the tank. It looks like the pump has 3 wires on it (original?). Within the last 1000 miles it has new distributor cap, rotor, plugs, wires, exhaust manifolds resurfaced, transmission rebuilt (puking fluid when hot). KOEO codes stored is 542 2 times, nothing else. The chart I looked at says "fuel pump open, bad ground or always on--Power / Fuel Pump Circuits". I have no idea how long those codes have been there or if they are induced by jumping pin 6. I have not been successful in retrieving the KOER codes.
Any suggestions as what my problem is?? I know that the fuel pump is a common problem but I would like to know FOR SURE what the problem is BEFORE throwing money at it.