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240 warm up loss of power

Submitted by dyelot99@sjv.net on 6 May 2008 - 4:22pm.
My 1982 240 D will loose power shortly after warming up, particularly noticable when attempting to accelerate or go uphill. During these times I can manually downshift the automatic transmission and the engine speed does not respond. Once I crest the hill and reach 45 miles per hour there is a sudden surge in power. I have changed all filters, and two different diesel mechanics in our area cannot figure it out. The car is a wvo conversion, and the same phenomenon occurs wether on diesel or veg. On a cold morning or when the car is first started this does not occur. Any suggestions?
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More details needed to help diagnose the problem

7 May 2008 - 8:31am
Kent Bergsma

Answers may help narrow down the problem:

1. What conversion kit do you have?

2. Are you running a aux. electric boost fuel pump?

3. How long have you been running on WVO?

4. How long has this been going on?

5. Was there anything done to the car just before it started losing power?

6. Have you done any recent maintenance other than filter changings ie. valve adjust, clean injectors, cleaned tank screen, etc.?

1. Is a Greasecar

7 May 2008 - 2:30pm
dyelot99@sjv.net
1. Is a Greasecar conversion. 2. No aux pump. However, problem happens when running on diesel only, and when running veg. 3 WVO about 20K 4. Problem started last fall, cleared up in the winter, and is starting agian now that its finally warm. 5. Not that I recall. 6 New injectors when greasecar kit installed. All filters changed very recently. Valves adjusted 3K ago, at same time injectors pulled and cleaned. Additional info. Car acts as if fuel or air starved when accelerating uphill. Large amount of black smoke and engine gets really hot. After finally getting to about 45 mph its as if someone opened the air intake and a sudden surge of power pushes you back in the seat, the black smoke goes away and the engine runs great. Thanks for your thoughts, Joel

Sounds like fuel starvation

7 May 2008 - 4:25pm
Kent Bergsma

From your description sure sounds like fuel starvation (loss of fuel pressure). This could be due to something not working properly in your conversion hose routing, valving, etc or something in your fuel injection pump.

You need to find out if the problem is happening before or after fuel enters your lift pump (bottom on injection pump).

If it were my car I would hook up a small fuel tank (1 gallon) in the engine compartment with fuel return going right back into the make shift tank. Just like doing a diesel purge. This would bypass your entire existing fuel system. Then I would drive it up a hill. If the problem goes away then the problem is in the fuel system. If you still have the problem then suspect first the mechanical lift pump (worn out) or the injection pump itself (WVO contanmination from marginal conversion).

One other thing: This is a long shot but worth checking - if you continue to be stumped by the problem a restricted exhaust system (ie plugged muffler) can cause these type of symptoms (especially the engine overheating under load).

1984 300SD warmup loss of power

1 June 2008 - 9:21pm
Mark Ristau
I have the EXACT problem but I do not use WVO and my car is a 1984 300SD. When it is cold it seems to run fine. Once it warms up I have the problem. In addition it also runs rough at idle after warming up, like a gas engine missing on one cylinder.