Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Mysterious loss of acceleration

I submitted the following request for specific help to Tom & Ray to learn that they may not be able to reply. Anyone out there able to respond? Many thanks.


11.02.08. Dear Click/Clack:

Your show is good listening. Beats a cup of coffee to keep alert as the miles spin away. I presently find myself in need of your help.

It?s Sunday and I am sitting outside my Dodge Dealer awaiting tomorrow?s opening of the Service Department where a leaking fuel line was replaced on Friday on my 2003 Sprinter van purchased new at the beginning of ?04. (Model 2500SCH) The worn CAC hose (black goop oozing out) was also replaced. The van has a Mercedes diesel engine. It is a camper conversion van that I live in 25 hours/day. (see attachment). It has just under 80,000 miles. Maintenance work has been done religiously at astounding cost.

After repairs on Friday, when the tech returned from a test drive, I was told that there was diminished acceleration for passing. It was suggested that something was wrong with the transmission. I was asked if I had noticed any problem. I had not. It was late in the day and I settled my bill and left. I was flabbergasted! Acceleration is so unresponsive as to be dangerous when merging onto the interstate- a malfunction that could not have been missed had it existed previously.

More info: The diesel was leaking out the top where the fuel line attaches. I have not asked if there was any other damage to the replaced line. The previous week I had attempted to have the problem attended in Fresno (CA) but the Dodge Dealer there couldn?t get the part for three days. I think he should have put a band on it as a temporary fix where there was no clip and the leaking was obvious. At any rate, it had stopped leaking at that point and it was cranking over with no problem. Since I needed to get an absentee ballot in Marin County I drove 250 miles north. No problems whatever during this phase. I drove for a couple more days with no trouble and then the original problem of the engine not wanting to turn over reoccurred indicating renewed leak (small). I brought the machine to the Dodge Dealership in Petaluma- a 30 minute drive on the interstate. When I stopped at their door the fuel started to gush out.

Can you offer a diagnosis and suggest a genesis?

While I?ve got your ears… Is it possible for the fuel line to have been damaged or incorrectly attached when the serpentine belt was replaced? Would it have been detached during installation of the belt, for example? Just after that the original leak occurred I took it to a Mercedes repair shop in Mill Valley where they jerry-rigged it with an extra piece of tubing. They did not band this piece at the point of attachment. I must ask them if there was no clip on the fuel line at that point.

I have never heard you comment on Sprinter vans. I empathize with the service people as everything seems to be too tightly packed in.

The first thing that comes in mind concerning power loss in a diesel is air in the system, second is incorrect pump timing, third is a pump failure, then fuel quality.

Fuel should not leak. If it does, the hoses are worn/broken, improperly sized, or installed badly. If you showed the leak to any service department at a dealer, and they did not correct the leak, report them to a regional office, or the State Air Quality office. This is a definite no-no in any state in the country.

In regards to the hose potentially damaged in the process of replacing the serpentine belt, it could happen but only if the mechanic doing the work was completely incompetent. I just did mine in about 10 minutes and no fuel lines were disturbed or touched in the process.