W202 1997 C250TD fuel starvation??

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Harvey
Dernburg Wagon
Posts: 9
Joined: Wed 13 Apr, 2016 5:03 am
Model you own: w202

W202 1997 C250TD fuel starvation??

Post by Harvey » Sat 22 Sep, 2018 7:53 pm

Dear Brains Trust
I run this car on 95-100 % wvo filtered to 5micron, (dash of misfuel in winter) (Brisbane).
Water injection when boost >7psi
With or without the injection, at low rev high boost less so, but high rev 2500rpm I get surging feels like fuel starvation.
Changed fuel filter, cleaned prefilter (the one in the top of the fuel filter housing). Installed a glass prefilter before the heat exchanger so I could hopefully see what’s going on.
Still get surging at 2500 rpm.
Unsure as to whether the car has an in tank filter that may have a restriction I hooked air compressor up to the line from engine bay to the tank. Applied 7 bar !!! and it held pressure. Listened at fuel filler cap and no sound of bubbles.
1. Does this car have a one way valve at or near the tank that would stop the pressure I applied to clear the line??
2. What to try next?
Ideas will be greatly appreciated
Kind regards Harvey

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SantoC
Pagoda
Posts: 124
Joined: Fri 10 Jul, 2009 10:07 am
Model you own: w124
Region: New South Wales
Location: Sydney

Re: W202 1997 C250TD fuel starvation??

Post by SantoC » Wed 26 Sep, 2018 1:21 pm

Harvey wrote:
Sat 22 Sep, 2018 7:53 pm
Unsure as to whether the car has an in tank filter that may have a restriction I hooked air compressor up to the line from engine bay to the tank. Applied 7 bar !!! and it held pressure. Listened at fuel filler cap and no sound of bubbles.
On my C250TD, there is a one way valve on the fuel line (just left of the PO installation of a prefilter) - located near the tank.
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Harvey
Dernburg Wagon
Posts: 9
Joined: Wed 13 Apr, 2016 5:03 am
Model you own: w202

Re: W202 1997 C250TD fuel starvation??

Post by Harvey » Wed 26 Sep, 2018 9:44 pm

Dear Santo
Thanks for your help
I recall seeing that little device and wondering what it was. A non return valve makes sense.
Tomorrow I will put the car on stands, use compressed air to clear from the non return valve to the tank, and non return to engine bay.
Hopefully then I can get enough fuel flow .
After that, thinking maybe try removing the lift pump??
Don’t know if there could be a restriction there, or something at the injection pump??
Thanks mate for your ideas on where to start the trouble finding process

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Tony From West Oz
OZBENZ moderator
Posts: 3234
Joined: Mon 20 Jun, 2005 9:04 pm
Model you own: w202
Location: Bedfordale WA

Re: W202 1997 C250TD fuel starvation??

Post by Tony From West Oz » Sun 07 Oct, 2018 12:05 am

There could be an air leak causing a small amount of air to be sucked into the fuel system at high fuel flow situations. Check out ring a in fuel system before the fuel lift pump.
Alternatively and 10% UP to the fuel and compare performance.
Please report back
Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (SOLD)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

Harvey
Dernburg Wagon
Posts: 9
Joined: Wed 13 Apr, 2016 5:03 am
Model you own: w202

Re: W202 1997 C250TD fuel starvation??

Post by Harvey » Wed 10 Oct, 2018 9:52 pm

Removed One way valve, it allowed two way flow.
Flow from tank a trickle. Gave it a blast of compressed air and flow increased x 5.
I had a facet pump already located at the tank (as a solution to the 1/4 tank run dry problem) that I can switch from the cabin, so chucked the one way valve and put the pump in the delivery line to the engine bay. Figure this will assist bleeding fuel through to the lift pump and myriad of o rings that are problematic, which it did.
Changed OEM fuel filter, installed a CAV filter before the lift pump (thinking that if needed I now have the facet pump to create a positive pressure fuel system as opposed to a negative pressure system reliant on the lift pump), and that I likely have some sort of crap in the tank that partially blocked the outlet, but don’t want to drop the saddle tank to clean it out.
Current results is no more fuel starvation, and no need to turn on the facet pump, but I like the idea of having it as the fuel system in this car, with so many o rings prone to leak and allow ingress of air.
The two lines from each tank that I installed to alleviate the 1/4 tank empty problem I have just joined together, hoping they will naturally cross flow to maintain common level of each side. Wishful thinking I know.
I find the fuel gauge in the car totally unreliable (sender units gummed up with VO?) as to being able to verify if the venturi’s work and 1/4 tank issue exists, so I zero odometer when I fill up, and refuel when odometer between 250 to 350km.
Plan is if I get fuel starvations again, turn on facet pump, check CAV filter, especially bowl to see what crap is coming through, change cav filter cartridge and proceed.
The cav filter cartridges are a fraction of the cost of OEM or equivalents.
Will appreciate any comments on my plan :dontknow:

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Tony From West Oz
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Posts: 3234
Joined: Mon 20 Jun, 2005 9:04 pm
Model you own: w202
Location: Bedfordale WA

Re: W202 1997 C250TD fuel starvation??

Post by Tony From West Oz » Thu 11 Oct, 2018 11:22 pm

Harvey, Sounds good, but joining of the two tanks with a hose is unlikely to be any good for overcoming the 1/4 tank issue, especially if they go over the driveshaft & exhaust pipe.
Might be OK going under them, but then risk the hose fouling road debris, rapidly providing an empty fuel tank and a oily trail on the road.
Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (SOLD)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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