Thread: Isuzu fuel pump died??

David, It's highly unlikely the main injector pump has died. They last forever. Most likely the lift pump is the problem. You didn't elaborate on what happened so I can only guess that it starved for fuel and slowly died. Usually you don't have to bleed the lines if the lift pump is in good condition but crack the return line at the top of the fuel filter housing and operate the lift pump primer by hand until fuel starts flowing. If nothing happens I would go back over the fuel lines looking for an air leak in the suction line first. If everything looks ok I would unbolt the lift pump of the main pump housing and check it out. Most likely it will be the problem. Spares are readily available from Isuzu dealers. Part number is 8941327070 which includes the hand primer. Part number for the primer is 8941311300. I have seen them on ebay for $15 I think, they are a generic style and fit a number of pumps.

on the underside of the lift pump is the hidden strainer no-one remembers to clean after they do a fuel system clean up. Its hidden inside the bolt that holds the union fitting that supplies the fuel to the lift pump.

the fuel water seperator could be leaking.

the easy priming method for the suzi is to

• crack the top nut on the fuel filter (the one thats the return line from the injectors/injector pump)
• pump the hand priming pump till that gets a good clean flow.
• lock the top nut up
• crack the HP injector union nuts on injectors 2+4 then
• with someone holding the accelerator flat to the floor (eye protection and gloves on for this next bit)
• crank the engine on the starter till you get fuel spurting from 2+4 injector unions. (by this time the engine should be trying to run on 1+3)
  AS SOON AS THE ENGINE STARTS (it will be running very rough at this stage) have your assistant ease off of the throttle till high idle (bout 900-1000 RPM) is maintained
• lock up the unions on 2+4
• if its still running rough crack 1+3
• Providing nothing else is fouling the fuel system, nothing is leaking air before the lift pump and all injectors/injection pump are still servicable it should take less than a minute for the engine to go from starting to fire to smooth idle.

Thanks for the idea's.
What specifically happened is it had all the symptoms of a fuel starvation at 100kph just before a town, so I called in to the servo & bought an 8" shifter as I thought I might need to clean out the main paper filter. I never had any tools, such is my Isuzu confidence
It seemed to clear away but there is a really long hill just before the Phillip Island turnoff about another 10k on & she started to run like a bucket 3/4 way up, so I turned in to a bus stop at the top there.
I removed the paper filter but it seemed pretty reasonable but then couldn't restart it & neither could the RACV guy- athough he admitted little diesel knowledge. I did wonder why he tried Aerostart.
Justin later explained about the primary filter which, sure enough, was clagged up.
It now appears the primer plunger has no compression. From what you say Brian, this can be replaced? Does it unscrew?
Sorry for the dumb questions, but I admit being an Isuzu newbie.
Regards,
David

Originally Posted by DeeJay

Thanks for the idea's.
What specifically happened is it had all the symptoms of a fuel starvation at 100kph just before a town, so I called in to the servo & bought an 8" shifter as I thought I might need to clean out the main paper filter. I never had any tools, such is my Isuzu confidence
It seemed to clear away but there is a really long hill just before the Phillip Island turnoff about another 10k on & she started to run like a bucket 3/4 way up, so I turned in to a bus stop at the top there.
I removed the paper filter but it seemed pretty reasonable but then couldn't restart it & neither could the RACV guy- athough he admitted little diesel knowledge. I did wonder why he tried Aerostart.
Justin later explained about the primary filter which, sure enough, was clagged up.
It now appears the primer plunger has no compression. From what you say Brian, this can be replaced? Does it unscrew?
Sorry for the dumb questions, but I admit being an Isuzu newbie.
Regards,
David

Definitely sounds like starvation. The most likely suspects are
1......primary fuel filter
2......gauze strainer on bottom of lift pump
3......fuel tank pickup strainer blocked
3......main fuel filter
4......lift pump or primer u/s
The primers are replaceable and simply unscrew, but I would check it first by cracking the injector return line and give it about 20-30 pumps. Even from new they dont seem to have much resistance. As Dave said the fine gauze strainer at the inlet side of the lift pump is a main offender. Undo the dome nut and check it, your symptoms sound like it (under load going up a hill). You will be surprised how much crap makes it past the primary filter/sedimenter. If the lines are dry it may take a bit of hand pumping to get the fuel back through the filters and pump. If the filters and the gauze strainer are all ok, disconnect the fuel inlet pipe before the lift pump and with a bit of rubber hose run a line from a jerry can or tin of diesel and reprime it. If it works you know the problem is in the lines or the tank pickup/strainer. I pulled the tank strainer off mine and now any crud in the tank gets to the primary filter/sedimenter instead of blocking the pickup. Much easier to replace the filter than pull the tank out and clean that mesh sock on the pickup.

Thanks Brian,
There's a couple of good idea's there, I'll give it a try tomorrow.
I wasn't aware of the lift pump filter either.
There's SFA in the Isuzu manual...
Cheers, David

You will find that the filter on the bottom of the pump can be serviced without removing the engine - but it is not easy. There is a good reason why it is rarely touched!

John

Originally Posted by JDNSW

You will find that the filter on the bottom of the pump can be serviced without removing the engine - but it is not easy. There is a good reason why it is rarely touched!

John

That's the main reason I fitted a filter before the pump. On the weekend I removed and cleaned the sedimenter. I found about 5 mm of sludge at the bottom. I only cleaned it about 18 mths ago.

Just a note on the lift pump. Mine was knackered and Isuzu wanted over $100 for one. I bought a generic one on eBay as suggested above for $15 plus postage. They are available in two types (plastic & metal) through the same supplier.

Here's the one I bought:

DIESEL HAND PRIMER SPRING TYPE - TOYOTA NISSAN ISUZU - eBay 4x4 Accessories, Exterior, Car, Truck Parts, Cars, Bikes, Boats. (end time 30-Oct-10 15:34:11 AEDST)