1990 Fiat Ducato 2.5 diesel low on power (1 Viewer)

Pipflip

Free Member
Mar 7, 2021
5
2
Muswell Hill London
Funster No
79,596
MH
Fiat Ducato 1990
Exp
A few days
Hi everyone , I have just joined !
My son turned up the other evening with a Fiat motorhome ( a really long one ! ) a swift Kontiki 6 berth 70k miles on the clock ( It has not gone very far in the last 10 years ). The first and major issue was that having driven from Wales to London , in the last 20 miles power dropped off to the point it was down to 20mph on hills. My initial inspection revealed a badly set up throttle cable and stiff injector actuator arm now resolved. The engine seemed to rev well but on trying to transfer the van to my industrial unit with parking it was much worse so I ended up towing him there !
I dont have much experience with diesels but have "spannered" many engines in the past being a Jag fan.

From reading the useful posts on this forum water in the fuel seems the most obvious culprit ( there is water everywhere else ! ) and as the van had been idle for a long time Ill start with the fuel filter. Can anyone advise on how to drain the fuel pump / mechanical injector ? I might even set up a remote tank. If no luck there Ill pull the injectors and maybe have them tested but probably best to have the injector pump and injectors calibrated at the same time ?.

On a more fundamental basis , I have a compression tester ( for petrol engines) . Does it screw into the injector holes or glow plug holes ?? Ill need to get a manual.

Any initial advice /pointers would be appreciated.

Pretty much everything else on it needs a overhaul so Ill be back on soon .

Thanks

Simon
 

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Jul 4, 2018
1,176
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Bristol
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54,738
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Weinsberg
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A few years.
Fuel filter and prime the system should have a rubber bulb in the fuel line near the filter or a piston on top - you will see it. Could be as simple as old Diesel and gunge from the bottom of the tank, fingers crossed for you.
 
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Jul 6, 2009
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Be aware pulling injectors on this engine, only do it after you have tried everything else. Check the rubber hose from the air filter to the engine has not collapsed. temporary remove the paper air filter element, its not unkown for mice. To get in and chew it so it collapses or the mouse gets sucked in, change the fuel filter

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Jul 24, 2015
374
947
Ramsgate Kent
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37,263
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Fiat ducato c class
Exp
5 years
As above.. definitely change the fuel filter and air filter before anything else..I've had the paper Air filter rotted out on an early fiat I just picked up..sucket it through 😔 .

Water in the fuel filter is common also.

Once you've changed them both give it a good hiding 👍🏼
 
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Clipgate

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Jan 1, 2014
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A petrol engine compression tester is absolutely inadequate. Mind you if your not nearly the resulting bang will be interesting,
 
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Clipgate

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Typical diesel engine direct reading pressure is in the region of 230 psi give or take

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pappajohn

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Aug 26, 2007
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Since 2005
On a more fundamental basis , I have a compression tester ( for petrol engines) . Does it screw into the injector holes or glow plug holes ?
Neither.....
A petrol engines compression ratio is usually about 7-1 (seven times atmospheric pressure) where as a diesel engine compression ratio can be 19-1.... 19 times atmospheric pressure.
A petrol tester won't survive the diesel pressure.
A comp tester will go in the injector holes.... The glow plugs are generally too small.
 
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Pipflip

Pipflip

Free Member
Mar 7, 2021
5
2
Muswell Hill London
Funster No
79,596
MH
Fiat Ducato 1990
Exp
A few days
Thanks for all the comments . Very useful. There is in fact no air filter fitted !! but given the condition of everything else there is probably water/sludge in the fuel and I doubt the fuel filter has been changed for eons but Ill get to the vehicle in the next few days and report back.

Thanks

Simon
 
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Pipflip

Free Member
Mar 7, 2021
5
2
Muswell Hill London
Funster No
79,596
MH
Fiat Ducato 1990
Exp
A few days
Hi All
We have had another look at the van today.
The fuel filter has a drain plug at the bottom ( presumably for draining water ) I have drained the filter and there was indeed some water at the bottom but we also put a new filter in ( primed with diesel). There was no air filter but I cant fit the new one as it seems the clamp plate is missing ( butterfly nut is still on though so is it the correct air filter ?). As the battery level was not known I used a tad of easystart just whilst all the air locks cleared,. The engine idled and revved as one would expect.

The problem is that I think the issue is when the engine is hot. I had fitted a remote tank but we have found the rear tyre is flat and the spare is awaiting a new tyre !

So the question is , what would cause good cold running but poor hot running ? The van ran ok for 170 miles back from Wales but lost power in the last 20 miles so something has blocked or broken or suddenly become worn. Temp gauge was not connected but is now. If the engine had overheated it would be noticeable ( smell + loss of water) and does not explain why it starts idles and revs ok when cold and not hot. There are no worrying mechanical noises and other than a bit of smoke at start up there is surprisingly little smoke at idle and when being revved ( when cold ! )

I took the fuel filter home and cut it open it was not full of gunge but the paper was black. At this stage I do not suspect the fuel filter or the small amount of water in it.

I also noticed 2 sets of electrical connections to the fuel filter housing. The top one looks like a pressure sensor ?? but no clue on the bottom one BUT the Black white wire with the new crimped connection was loose. Its now back on but again due to the flat tyre I can test the van on the road yet.

There was also what looked like a pressure sensor on the actual injector pump.

My next course of action is to change the wheel and take it for a run using the temp tank but I can also rule out the low pressure fuel pump by bypassing it. I really need to understand the control system and if any of the wiring is relevant so if anyone has had the low /normal temp running issues or any suggestions as to cause I would again be most grateful.

Thanks

Simon

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Pipflip

Pipflip

Free Member
Mar 7, 2021
5
2
Muswell Hill London
Funster No
79,596
MH
Fiat Ducato 1990
Exp
A few days
Hi All
The problem is solved. The temp tank returned good power ( in fact better than before ) I was not sure if the cure was the new fuel filter so we switched back to the fuel tank and power reduced to nothing. When I went to check the water drain on the fuel filter there was a hissing noise as air was sucked in !
Switched back to the temp tank and full power was restored.

There must be a ton of crud in the tank so that will either be replaced or cleaned out.

Thanks for all the help , I am sure Ill be back .

Simon
 
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MisterB

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Feb 25, 2018
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enough to know i shouldnt touch things i know nothing about ....
ive had this with a couple of vehicles (cars) changed the fuel filter and zoooooooommmmmmm .......
 
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Campervan_man

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There can also be microbes living in the fuel tank { a bit like diesel jelly fish } that float around the tank and block everything up. *Drop the tank and flush it out.*

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