M
madmac
New member
Hello, I am new to the forum and I am looking for some advice on a problem I can't diagnose on my 88 3CX backhoe with a Perkins engine. I hope there are well-seasoned diesel engineers here that can help!
I bought the machine as a non-runner a few months ago. Previous owner said it ran great but lost power then wouldn't start. It was cheap enough and in pretty good shape so I took a punt.
I found the fuel filter was clogged up, so started at the tank, cleaned the strainer, lift pump gauze, sight glass bowl, new filter cartridge, cleaned out all the lines and tank, and replaced the gauze in the inlet to the injector pump. There's good fuel flow now. It look ages to bleed the pump and injector lines. I eventually got fuel mist at the exhaust but despite a lot of cranking it just wouldn't start. I eventually got it running by pointing a blowtorch up the inlet manifold and got a few 'coughs'. It took about 5 minutes and it eventually started. It ran great, no smoke, good throttle response, plenty power, all good. She sounds healthy.
I shut it off after 20 minutes running to check the rest of the hydraulics. It then wouldn't start after a few minutes, even when fully warmed up.
After much cranking, blowtorch etc I still couldn't get it to fire up. I replaced the feed pump vanes/ring and plunger assembly in the injection pump, removed the top cover to check the shutoff mechanism wasn't stuck, which it wasn't, and replaced the electric shutoff solenoid just in case (which is getting power, and clicking as it should).
After a lot more cranking and using the blowtorch again today I got her started again from cold. She did 3 hours scraping the driveway, lifting pallets etc and didn't miss a beat. I thought it might be fixed, yay!
I then shut it off (on the key) and tried to restart it literally 5 seconds later, and it cranked OK, but didn't fire once. There was a little smoke out the exhaust though.
The pump still has a mechanical shut off, but the solenoid on the pump seems to be doing its job - I've not had to use the mechanical stop, and have confirmed this isn't stuck internally.
I have to suspect something internal to the pump, to do with the shutoff system. My experience with these CAV pumps and systems tells me if there was an air leak in the lines/filter up to the pump, it would still start, then stop as air reaches the pump, but between shutting off and trying to start was a matter of seconds, so I'm ruling out any bleed back or air leak for now. The engine was warm, so any cold start system shouldn't be needed anyway.
Anyone have any other ideas? Could it be an injector problem?
I'm reaching the point of removing the injector pump and sending it away for a rebuild. Access to the pump drive looks like it'll be a pain in the ass though.
I appreciate any suggestions to anything I may have overlooked!
Donald
I bought the machine as a non-runner a few months ago. Previous owner said it ran great but lost power then wouldn't start. It was cheap enough and in pretty good shape so I took a punt.
I found the fuel filter was clogged up, so started at the tank, cleaned the strainer, lift pump gauze, sight glass bowl, new filter cartridge, cleaned out all the lines and tank, and replaced the gauze in the inlet to the injector pump. There's good fuel flow now. It look ages to bleed the pump and injector lines. I eventually got fuel mist at the exhaust but despite a lot of cranking it just wouldn't start. I eventually got it running by pointing a blowtorch up the inlet manifold and got a few 'coughs'. It took about 5 minutes and it eventually started. It ran great, no smoke, good throttle response, plenty power, all good. She sounds healthy.
I shut it off after 20 minutes running to check the rest of the hydraulics. It then wouldn't start after a few minutes, even when fully warmed up.
After much cranking, blowtorch etc I still couldn't get it to fire up. I replaced the feed pump vanes/ring and plunger assembly in the injection pump, removed the top cover to check the shutoff mechanism wasn't stuck, which it wasn't, and replaced the electric shutoff solenoid just in case (which is getting power, and clicking as it should).
After a lot more cranking and using the blowtorch again today I got her started again from cold. She did 3 hours scraping the driveway, lifting pallets etc and didn't miss a beat. I thought it might be fixed, yay!
I then shut it off (on the key) and tried to restart it literally 5 seconds later, and it cranked OK, but didn't fire once. There was a little smoke out the exhaust though.
The pump still has a mechanical shut off, but the solenoid on the pump seems to be doing its job - I've not had to use the mechanical stop, and have confirmed this isn't stuck internally.
I have to suspect something internal to the pump, to do with the shutoff system. My experience with these CAV pumps and systems tells me if there was an air leak in the lines/filter up to the pump, it would still start, then stop as air reaches the pump, but between shutting off and trying to start was a matter of seconds, so I'm ruling out any bleed back or air leak for now. The engine was warm, so any cold start system shouldn't be needed anyway.
Anyone have any other ideas? Could it be an injector problem?
I'm reaching the point of removing the injector pump and sending it away for a rebuild. Access to the pump drive looks like it'll be a pain in the ass though.
I appreciate any suggestions to anything I may have overlooked!
Donald
