A
AEkrot
Guest
I think that I just experienced what TurboJim described in his reply to the post "Injector Duty Cycle Calculations by FAST" about a fuel pump failure.
I recently upgraded from a XX Mondo to a Procharger F3 on a 347 CID SB. I upgraded my fuel system at the same time from 2 SX pumps (I am told they are basically the same as the Aeromotive A1000) to a single Weldon 2035.
First time out with the new combination was this past Friday due to all the rain we've had in Houston the past 3 weeks.
I was way too rich on the first pass: <9:1 but I got things lined out in 3 passes (+/- 5% WB O2 Correction). These were 1/4 mile passes. I saw 30 psi boost at 8200 rpm and went 9.0 at 157 mph on a cold, dew covered track (I had to do some steering at the 1000' mark
) with a fixed 19 degree timing curve (3250#).
The next day, I went to a local 1/8 mile track to work on adjusting my suspension to handle more timing at launch. The first 2 passes were fine motor-wise (spun to a 5.6 at 128). On the 3rd pass, the car nosed over just after I shifted 2nd gear (mid track) and I got out of it immediately. I didn't note the oil or fuel pressure since I was steering a lot to go straight (20+ mph cross wind that afternoon). The video tape of the run shows no smoke at the point of failure but the engine "sounded" very different, like it was running out of gas (I didn't think that at the first time I listed to it but it is definitely NOT an "ignition gone bad" sound with popping or breaking up).
What I saw on the data log was WOT (tps 88%; boost climbing together with rpm; then the rpm and boost began falling. The O2 Correction was maintaining +/- 5% and my correction limits were set for -15%, +15%. When it nosed over it felt earily like a motor seizing up
so I checked the oil for metal.
The oil was fine (even out of the filter), plugs looked fine. So I cranked the car and verified oil pressure was ok. It seemed like it took forever to fill the new filter up with oil and build pressure but it eventually did (about 30 seconds) so started it with the dashboard active. Car started and idled fine but the second I tried to give it any gas at all, it "bogged" like a carbureted car with a bad accelerator pump.
I verified my tps was working - all other sensors read normal readings, (AT, WT, O2). Then I noticed the fuel pressure wasn't quite 60psi which is were I set it. When I gave the car some gas I noticed it fluxuated down a couple psi. When I powered up the pump and watched the guage, it didn't instantly peg 60 like it did when I first installed it, instead, it went up to 30 then slowly climbed up to 58 or so but it sounded the same as when I first installed it.
I then thought I ran the car out of gas but found a nearly full cell so I then checked the fuel filters. I have a 40 micron pre-filter between the fuel cell with -12AN inlet line and a 10 micron outlet filter with -10AN line to the front fuel block and I use a funnel with a 50 micron? screen cartridge in it - I have a 1 year old plastic fuel cell. Lot's of spilled fuel later, I found that the filters looked fine so I tried it without the filters installed - SAME THING.
I'm pretty sure I have a pump that went south but can still make 58 psi given enough time but it can't flow significant volume anymore.
What do you guys think? I didn't have time to try disconncting the return line to watch how much fuel come out...
Alex
I recently upgraded from a XX Mondo to a Procharger F3 on a 347 CID SB. I upgraded my fuel system at the same time from 2 SX pumps (I am told they are basically the same as the Aeromotive A1000) to a single Weldon 2035.
First time out with the new combination was this past Friday due to all the rain we've had in Houston the past 3 weeks.
I was way too rich on the first pass: <9:1 but I got things lined out in 3 passes (+/- 5% WB O2 Correction). These were 1/4 mile passes. I saw 30 psi boost at 8200 rpm and went 9.0 at 157 mph on a cold, dew covered track (I had to do some steering at the 1000' mark
) with a fixed 19 degree timing curve (3250#).The next day, I went to a local 1/8 mile track to work on adjusting my suspension to handle more timing at launch. The first 2 passes were fine motor-wise (spun to a 5.6 at 128). On the 3rd pass, the car nosed over just after I shifted 2nd gear (mid track) and I got out of it immediately. I didn't note the oil or fuel pressure since I was steering a lot to go straight (20+ mph cross wind that afternoon). The video tape of the run shows no smoke at the point of failure but the engine "sounded" very different, like it was running out of gas (I didn't think that at the first time I listed to it but it is definitely NOT an "ignition gone bad" sound with popping or breaking up).
What I saw on the data log was WOT (tps 88%; boost climbing together with rpm; then the rpm and boost began falling. The O2 Correction was maintaining +/- 5% and my correction limits were set for -15%, +15%. When it nosed over it felt earily like a motor seizing up
so I checked the oil for metal.The oil was fine (even out of the filter), plugs looked fine. So I cranked the car and verified oil pressure was ok. It seemed like it took forever to fill the new filter up with oil and build pressure but it eventually did (about 30 seconds) so started it with the dashboard active. Car started and idled fine but the second I tried to give it any gas at all, it "bogged" like a carbureted car with a bad accelerator pump.
I verified my tps was working - all other sensors read normal readings, (AT, WT, O2). Then I noticed the fuel pressure wasn't quite 60psi which is were I set it. When I gave the car some gas I noticed it fluxuated down a couple psi. When I powered up the pump and watched the guage, it didn't instantly peg 60 like it did when I first installed it, instead, it went up to 30 then slowly climbed up to 58 or so but it sounded the same as when I first installed it.
I then thought I ran the car out of gas but found a nearly full cell so I then checked the fuel filters. I have a 40 micron pre-filter between the fuel cell with -12AN inlet line and a 10 micron outlet filter with -10AN line to the front fuel block and I use a funnel with a 50 micron? screen cartridge in it - I have a 1 year old plastic fuel cell. Lot's of spilled fuel later, I found that the filters looked fine so I tried it without the filters installed - SAME THING.
I'm pretty sure I have a pump that went south but can still make 58 psi given enough time but it can't flow significant volume anymore.
What do you guys think? I didn't have time to try disconncting the return line to watch how much fuel come out...
Alex
and decided to change the plug wires since they were one year old and everything else was new. BINGO the problem was gone. I never seen wires go bad in a given RPM window before.
