1982 Euro 928s low fuel pressure and poor running
02-03-2019, 07:26 PM
#31
Racer
Thread Starter
I replaced the FD orings and reinstalled everything. After adjusting the AF screw out 12.5 turns from full tight, I heard two injectors sing slightly with the fuel pump running. I then turned the screw 1/8 turn ccw and tried to start.
I get a brief startup, and then the engine dies, and I’ve done this probably 20 times. My guess is that it’s just starting on the 9th injector. I haven’t checked for flow from the other injectors yet.
Fuel pressure was 75psi main and 35psi control. I’m not sure if I trust my tester though because it was blowing fuel out of the connectors. I only got pressure to register on the gauge if I held pressure on the connectors while running the pump. It also leaked down quickly from 75 to 55psi for system pressure, but wouldn’t release pressure below 35psi even with hoses disconnected and valves open. I hate $hitty equipment.
I don’t know what to do now. Mostly just because I’m tired of dealing with this engine. I am considering sending the FD and WUR to be tested/rebuilt by pros.
Camelman
I get a brief startup, and then the engine dies, and I’ve done this probably 20 times. My guess is that it’s just starting on the 9th injector. I haven’t checked for flow from the other injectors yet.
Fuel pressure was 75psi main and 35psi control. I’m not sure if I trust my tester though because it was blowing fuel out of the connectors. I only got pressure to register on the gauge if I held pressure on the connectors while running the pump. It also leaked down quickly from 75 to 55psi for system pressure, but wouldn’t release pressure below 35psi even with hoses disconnected and valves open. I hate $hitty equipment.
I don’t know what to do now. Mostly just because I’m tired of dealing with this engine. I am considering sending the FD and WUR to be tested/rebuilt by pros.
Camelman
02-03-2019, 09:44 PM
#32
Team Owner
I am considering sending the FD and WUR to be tested/rebuilt by pros.
Probably a good idea to put in fresh parts,^^^^
then you also replace the accumulator and fuel pump check valve if these parts have not been refreshed
Probably a good idea to put in fresh parts,^^^^
then you also replace the accumulator and fuel pump check valve if these parts have not been refreshed
05-25-2019, 04:51 PM
#33
I have the opposite problem I don't seam to be getting pressure to the injectors, there is fuel at the injectors, the car was running not reeving over 3000, found the problem was blocked fuel line, almost no fuel coming through, car stood for 2 years before I fixed it, car will run and rev if I put fuel in the air intake, but slowly dies as the fuel runs out, FD has been stripped and cleaned, fuel runs free to FD and tank and injectors, plunger is not stuck, cleaned injectors and they appear fine, has a new Bosch fuel pump, any suggestions ?
05-27-2019, 12:16 PM
#34
Racer
Thread Starter
Low full pressure, then a popping sound and pressure recovered
I’m back! I sent my FD to Salvox for a rebuild, but got oddly low fuel pressure readings upon reassembly. Then, my 944S2 blew a head gasket due to a badly corroded cylinder head and I stopped working on the 928s. The 944S2 is now repaired, so back to the 928s.
I found very low fuel pressure and very poor running with some black smoke after rebuilding the FD at Salvox. I thought my gauge was bad so I tried another. With the replacement gauge, I still registered low fuel pressure. I noticed the fuel pressure gauge needle was “wiggling” around 5-10psi with the pump jumpered on, so I kept the pump on. Then, after about 15 seconds I heard a “ting” somewhere in the engine bay and the fuel pressure jumped up to 68psi. Pressure drops very quickly when the fuel pump is turned off with a ticking sound occurring from the back of the engine that corresponds to the gauge needle jumping, and then falling again.
The fuel pressure was measured between the WUR and FD. Any idea what could cause that response? It definitely seems like there was a blockage that freed up.
new fuel pump and filter
new in-tank sock filter
rebuilt FD by Salvox with all injectors firing simultaneously
WUR cleaned up with no clog in the filter screen
new MB injectors
cleaned screen in the fuel supply line connector to the FD
brake booster vac line pulled and plugged
new vac lines throughout engine
new intake gaskets
Camelman
I found very low fuel pressure and very poor running with some black smoke after rebuilding the FD at Salvox. I thought my gauge was bad so I tried another. With the replacement gauge, I still registered low fuel pressure. I noticed the fuel pressure gauge needle was “wiggling” around 5-10psi with the pump jumpered on, so I kept the pump on. Then, after about 15 seconds I heard a “ting” somewhere in the engine bay and the fuel pressure jumped up to 68psi. Pressure drops very quickly when the fuel pump is turned off with a ticking sound occurring from the back of the engine that corresponds to the gauge needle jumping, and then falling again.
The fuel pressure was measured between the WUR and FD. Any idea what could cause that response? It definitely seems like there was a blockage that freed up.
new fuel pump and filter
new in-tank sock filter
rebuilt FD by Salvox with all injectors firing simultaneously
WUR cleaned up with no clog in the filter screen
new MB injectors
cleaned screen in the fuel supply line connector to the FD
brake booster vac line pulled and plugged
new vac lines throughout engine
new intake gaskets
Camelman