Fuel pressure question 1999 UG Nimbus

[dokworm]

I have a 1999 stock UG nimbus that is refusing to start, If I spray aerostart into the air intake, it will start and run for a few seconds and then stop.
I can hear the fuel pump kick in, but how much fuel pressure should these things have?
I disconnected the fuel at the injection rail, and fuel does come out, but not at what I would call high pressure, more like you would pour milk out of a carton. Should it really be 'spraying out' under a lot of pressure or is this normal?
I am thinking of ordering a fuel pressure tester but can't find what the pressure should be in any of the books. The ones for the 'spacewagon' all seem to be a different setup to the Aussie nimbus.

 

[4piknup]

Roughly it will be 37 or 43 psi.
As long as you get something like that you should be ok.
Sounds low, like a stuffed pump. It should spray 2-3m out of end of hose.

Are you getting voltage to the injectors?
Just put a volt meter on the wires to a injector. Should read 3v ish. And may bounce around a bit. A test light will flash as you crank it

 

[dokworm]

Thanks, that is exactly what I needed to know.
I stuck an oscilloscope on the injectors, and I'm getting what looks like a sensible pulse.
Disconnecting the fuel line at the rail, fuel comes out but would go maybe 10cm past the end of the hose when I jumper the relay. About the smae if I disconnect the line at the pump itself.
Sounds like it't time for a new pump.

 

[4piknup]

I only know from testing one in a bucket and im sure it hit the roof.I love my scope. Its a little dso single trace. Was $90 ish and size of a mobile phone.Bought it to see how much I would use it before spending up on a good one. It does everything I need and is so portable.Just make sure you are getting battery V to the pump, but it seems like you are on right track.Also you can use a oil pressure gauge to check fuel pressure but I wouldnt use a mechanical one as a permanent instal in side the car. Dont really need pressurized fuel pumped inside the cabin in the event of a accident...

 

[dokworm]

Mitsubishi wants $700 for the pump. I can get a denso one online for $95...

 

[dokworm]

I put in a new pump and filter and am still only getting the same pressure as before. Now I'm stumped.

 

[4piknup]

Bench test the old pump
Check for battery voltage at the pump connector
Check your under bonnet filter isnt blocked

 

[dokworm]

I get voltage at the pump connector, can't find an under bonnet filter.
If I disconnect the hose at the pump end, the pressure is about the same as at the injector rail, ie the fuel spurts out about a foot or so.
So it doesn't appear to be the lines/rail etc as the problem is the same at the pump end.
It it possible it is just really low pressure normally? I can't find any specs.

The pump is this one, same as on a heap of other cars, magnas veradas etc. (see bottom list)
http://www.ebay.com.au/itm/120800686565?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

[4piknup]

I might just delete all my posts and pretend I was never here.  

Bench test the old pump in a bucket of water or something.
My piss squirts out further than a foot. There something wrong.I know some later evo have dual speed pumps. But I wouldnt think you would have that and its still not enough pressure. What about volt drop? Measure with red lead on +ve battery and black on +ve at pump.Check the pump earth? Or volt drop again. Red on -ve at pump and black on good earth. Or run jumper wire .I cooked a connector to my pump. Must have just been a high resistance connection. But it melted it pretty good

 

[khubner1]

maybe the pickup is cloged and thus not allowing alot of fuel to enter the pump resulting in low pressure

 

[dokworm]

I'll check the voltage and do a bucket test today, I'll check the pickup line as well, it picks up from both sides of the tank from memory.

 

[dokworm]

It turns out that inside that pump/gauge assembly there is another part to it next to where the fuel pump connects that has a rubber o-ring to seal the end of the tube. That o-ring had collapsed and was blocking part of the outlet port. I replaced the o-ring and the car now starts, runs for about 2 seconds then stops.
Sometimes it will run for 30 mins or longer, but just stop randomly. The electrics all stay on, but the engine just stops.
Really weird.