Engine losing power - any ideas

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Hedgie
Member
Posts: 8
This is an intermittant problem that I have not been able to sort out for some time. While driving at about 90 -100kmh the engine progresively looses power until you struggle to get about 60kmh. Pressing on the accelerator there is no response under load but if you declutch the engine will rev okay, let clutch out and no response. This has occured in both warm and cool conditions on gravel and bitumen. I would stop and check everything, start up and all would be normal for a period of time, then it starts again. I have checked and changed the lift pump and all all filters in the system (4). Checked the fuel return and the pipe from the intake manifold to fuel pump. Thought it might not know the turbo was boosting and was not delivering enough fuel. Drawn fuel from different tanks and sources. The engine has done 177,000km.On most occasions it would occur on the last days of a trip as we headed home - just prefered staying in the bush?? When we get home the problem disappears or is not evident and can not seem to get it to happen when I can get to someone with greater wisdom.Could it be something in the fuel pump sticking and then releasing when stopped ? Had a look through David's VE injection pump links and I am hoping I don't have to pull that apart.
June 12, 2011 at 11:07 PM Flag Quote & Reply

Dandj
Member
Posts: 367
Could it possibly be a blocked air filter from an outback trip? This seems a popular cause of power loss.
Does it smoke at all (smoke colour can be an indicator of problems)?
Does it overheat or misfire?
Try a google search for "diesel loses power" (no quotes) and you'll see you are not alone, 19,700,000 hits, but rarely does the injector pump get mentioned, mostly fuel or air supply.
There's a very good Bosch VE Pump document available here because it might have a dodgy governor. But try all the simple things first.
Call a Perkins man and ask advice, such as Allen Wehrmann at AW Diesels on (08) 8347 0083. He knows Perkins and Oka's.
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David and Janet Ribbans, Oka 148

June 13, 2011 at 12:47 AM Flag Quote & Reply

Peter & Sandra James Oka 374
Member
Posts: 412
Check the breather in the fuel cap. If air cannot get into the tank to replace fuel used then eventually the fuel won't be able to be sucked out either.
When it plays up the next time open the fuel cap while it is running, if the air sucks into the tank as you release the cap then you've found the problem. especially if the engine is back to normal performance.
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Oka 374 LT Van

June 13, 2011 at 7:15 AM Flag Quote & Reply

Hedgie
Member
Posts: 8
Peter & Sandra James Oka 374 at June 13, 2011 at 7:15 AM
Check the breather in the fuel cap. If air cannot get into the tank to replace fuel used then eventually the fuel won't be able to be sucked out either.
When it plays up the next time open the fuel cap while it is running, if the air sucks into the tank as you release the cap then you've found the problem. especially if the engine is back to normal performance.
Checked the fuel cap/s and breathers and that was not an issue. Checked and cleaned the induction system and could find nothing there. Not running hot but is a bit smokey. When the issue arises and then stop it sometimes struggles to idle but then clears and idles okay. When it first happened I had to work the accelerator to keep it running but it seems to clear itself now.
June 13, 2011 at 8:36 AM Flag Quote & Reply

Dandj
Member
Posts: 367
I came across a rare but plausible cause, the fuel cut off solenoid on the injector pump only partially lifting.
Check the wiring to the solenoid to ensure it's fully working.
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David and Janet Ribbans, Oka 148

June 13, 2011 at 9:59 AM Flag Quote & Reply

deedy
Member
Posts: 18
If you havent already renew fuel filter/s.
Cheers
June 13, 2011 at 6:18 PM Flag Quote & Reply

Ewart & Vivian Halford
Member
Posts: 117
Are your fuel tanks clean. I came across a diesel years ago with a similar problem, it turned out the inner lining on the air intake pipe was peeling back, and would fall back into place once the engine was stopped.
June 13, 2011 at 7:25 PM Flag Quote & Reply

Dandj
Member
Posts: 367
This is the list of potential faults from the Oka manual. There's a couple here I hadn't thought of, especially the last one.
Lack of power
a) Primary filter blocked.
b) Secondary filter blocked.
c) Lift pump rod pushed down.
d) Collapsed fuel hose.
e) Air leak in fuel system.
f) Fuel change valve faulty.
g) Fuel shut off valve faulty.
h) Air leak from turbo boost line to the aneroid in the injector pump.
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David and Janet Ribbans, Oka 148

June 15, 2011 at 12:45 AM Flag Quote & Reply

oka422
Member
Posts: 7
As has already been suggested - are your fuel tanks clean. I had a similar problem with a petrol engine, a piece of plastic was floating around the tank, occasionally it would get caught on the fuel pickup pipe inside the tank and starve the engine of fuel. Could be similar to your problem, when your tank is near empty, there would be a greater chance of it being caught, turning off the engine releases the object.

June 15, 2011 at 11:01 AM Flag Quote & Reply

Hedgie
Member
Posts: 8
Thanks David and yes I have been through all the items on the list. When I took the boost line off I thought I had it when I cleaned it out and all went well - for about 50 minutes, I think it was just the stopping that did it but I did take it off again twice more just in case ! I have changed the lift pump and left the rod off in case it was sticking. Both the tanks are clean, the side tank I can see into and have pulled the pickup out. I have checked the fuel stop soleniod but that may warrant further investigation although it seems unlikely to slowly partially close.
June 15, 2011 at 6:17 PM Flag Quote & Reply

Aussie Bight Expeditions
Member
Posts: 109
Hedgie,
Just a thought that it could be the fuel stop solenoid if there are problems with resistance in the wiring system to it or there is a faulty solder joint as in a dry solder joint as these can take years to actually show a problem sometimes.
Maybe you could have a problem with the actual injector pump, not the first time I have seen that happen and give strange results, just seems strange that you can drive for say your 50 minutes and then it gives trouble , seem like a heating issue in something that lets something change and when you stop it changes for a certain time.
Unusual problem you have as you have covered nearly all the bases.
Since you have checked both lines to the divider of the fuel setup the next test is to put in a temp line either from the tank and / or from the divider and go to the steel line, that way you will eliminate all the hoses, and just put in a ryco filter throw away type to be the filter. I have done this with mine so I can pump fuel from the right tank to the left tank if there is something wrong with the switching mechanism, which has happened.
Normally I have found that when the fuel lines break down today it is more than likely they have been hit by an object and that is why they fracture inside. Have had that happen too, with doing drop offs for the DEC in the scrub over roads that have been bulldozed into the fire zone. That took a while to find and found by elimination of changing hoses, however the problem was the right tank and the way the factory set up is on mine if you loose power to the right hand tank the main line is the left tank and does not need any power to operate so it just works. I always use the right tank first for that reason as well as my safety line that I can pump from right to left.
You only get caught once in the scrub with a bus full of people and one tank empty and the other full and you can not use it, and only by changing fuel lines did I get home and wasted time trying to figure out what went wrong.
None of this might help your problem though.
Regards
ABE Tony
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June 16, 2011 at 9:46 AM Flag Quote & Reply

Aussie Bight Expeditions
Member
Posts: 109
Hedgie,
Just a thought that it could be the fuel stop solenoid if there are problems with resistance in the wiring system to it or there is a faulty solder joint as in a dry solder joint as these can take years to actually show a problem sometimes.
Maybe you could have a problem with the actual injector pump, not the first time I have seen that happen and give strange results, just seems strange that you can drive for say your 50 minutes and then it gives trouble , seem like a heating issue in something that lets something change and when you stop it changes for a certain time.
Unusual problem you have as you have covered nearly all the bases.
Since you have checked both lines to the divider of the fuel setup the next test is to put in a temp line either from the tank and / or from the divider and go to the steel line, that way you will eliminate all the hoses, and just put in a ryco filter throw away type to be the filter. I have done this with mine so I can pump fuel from the right tank to the left tank if there is something wrong with the switching mechanism, which has happened.
Normally I have found that when the fuel lines break down today it is more than likely they have been hit by an object and that is why they fracture inside. Have had that happen too, with doing drop offs for the DEC in the scrub over roads that have been bulldozed into the fire zone. That took a while to find and found by elimination of changing hoses, however the problem was the right tank and the way the factory set up is on mine if you loose power to the right hand tank the main line is the left tank and does not need any power to operate so it just works. I always use the right tank first for that reason as well as my safety line that I can pump from right to left.
You only get caught once in the scrub with a bus full of people and one tank empty and the other full and you can not use it, and only by changing fuel lines did I get home and wasted time trying to figure out what went wrong.
None of this might help your problem though.
Regards
ABE Tony
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June 16, 2011 at 9:46 AM