Double02 Posted September 8, 2017 Report Share Posted September 8, 2017 Since the car has only recently returned to the road, I'm working through various issues that keep popping up. Not sure if this is a diesel or general 604 question, so am asking it here. This one shows up intermittently, when the car is at over 90 km/h and under load. For lack of a better word it surges cyclically at a fairly low frequency, say around 3 cycles/second? It isn't alarming, but it is noticeable. When it happens, giving either more or less throttle makes it smooth out. Although it isn't noticeable at low speeds, it seems more load related than speed related as it doesn't happen when coasting. Also, this happens when the car is travelling in a straight line, not in curves. I'd appreciate any tips or thoughts on where to start looking. Quote Link to comment Share on other sites More sharing options...
Bean Posted September 8, 2017 Report Share Posted September 8, 2017 What kind of filter set up do you have? And does it have a manual prime button? I'm guessing it has to be fuel related, but you may also want to make sure the wiring and connector to the fuel shut off solenoid are in good shape. When I drove my td wagon back home from Calgary it would have a slight hesitation that progessively got worse. 12V supply wire to the solenoid was actually starting to short against the throttle cable. The wire finally welded itself to the cable a block from my house, but in doing so it melted all the way into the dash... It's now fused properly and rewired/fixed. Rabin Quote Link to comment Share on other sites More sharing options...
Double02 Posted September 8, 2017 Author Report Share Posted September 8, 2017 Good question, I have no idea but will check. Thanks. Quote Link to comment Share on other sites More sharing options...
Bean Posted September 8, 2017 Report Share Posted September 8, 2017 If it does have a priming button they usually have a diaphram in them - if they develop a hole it will start sucking air in - small air bubbles could / might be the cause. Once leak is big enough the IP will lose prime and it won't run. Depending on the filter set up, you may also want to check for water in the trap, as well as for the filter to be in good order. Rabin Quote Link to comment Share on other sites More sharing options...
Double02 Posted September 8, 2017 Author Report Share Posted September 8, 2017 This is my filter, so looks like it does have the priming button. Probably a good idea to replace it on a PM basis. Quote Link to comment Share on other sites More sharing options...
Goce Posted September 8, 2017 Report Share Posted September 8, 2017 I've experienced something similar and turn out to be exhaust hitting the floor pan, also my engine mounts ware shot and made things worse, check for exhaust and driveline touching the body. Quote Link to comment Share on other sites More sharing options...
Bean Posted September 8, 2017 Report Share Posted September 8, 2017 With that swanky (and $$$$) rebuilt pump you might want to replace the filter as PM, and inspect the diaphram. (Should disassemble easily enough) Another tip from the Mercedes TD guys is to run a cheap Inline pre-filter just to catch the big gunk and to also serve as a diagnostic aid since they're usually clear / translucent. Bosch VE injection pumps are supposed to be on the finicky side when it comes to diesel, so a good filter set up is good thing to stay on top of. Rabin Quote Link to comment Share on other sites More sharing options...
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