Misfire
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Joined: Dec 2025
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ML63
Misfire
Hi I recently rebuilt my ML63 engine during the build found out that one of the fuel pumps was leaking oil into the injectors right side and I replaced both fuel pumps with new genuine ones however now the car misfires on cold start and alittle smokie then when u drive it it’s hit and miss sometimes it drives good and sometimes it drives rough and jerks and pulsating.
I’m wondering if there is oil still in injectors and should I have changed them all?
also a mechanic told me it could be fuel tank pump
could anyone help me with this problem thanks.
I’m wondering if there is oil still in injectors and should I have changed them all?
also a mechanic told me it could be fuel tank pump
could anyone help me with this problem thanks.
Last edited by Charlieml63; Dec 17, 2025 at 03:14 PM.
Member
Joined: Jun 2025
Posts: 164
Likes: 58
From: Australia
2014 ML63, 2018 GLC43, 1929 DB victory six sports roadster
Hi I recently rebuilt my ML63 engine during the build found out that one of the fuel pumps was leaking oil into the injectors right side and I replaced both fuel pumps with new genuine ones however now the car misfires on cold start and alittle smokie then when u drive it it’s hit and miss sometimes it drives good and sometimes it drives rough and jerks and pulsating.
I’m wondering if there is oil still in injectors and should I have changed them all?
also a mechanic told me it could be fuel tank pump
could anyone help me with this problem thanks.
I’m wondering if there is oil still in injectors and should I have changed them all?
also a mechanic told me it could be fuel tank pump
could anyone help me with this problem thanks.
Thread Starter
Newbie
Joined: Dec 2025
Posts: 4
Likes: 2
ML63
ML63
Yes have hooked up scanner it came up intake camshaft sensor I’ve replaced it and scanner has no fault codes so only thing I can think of is injectors I took the injectors to a guy who tests them with high pressure machine but when he looked a one he said that they had oil in them and refused to put it in he’s machine and said that once there’s oil in them they should be replaced and that continuing to use them would eventually damage the engine I though he was saying that to try and sell me a new set of Bosch injectors thinking back he was probably right but can’t be sure that why I thought I’d try MB Forum does anyone have an idea of what it could be.
Member
Joined: Jun 2025
Posts: 164
Likes: 58
From: Australia
2014 ML63, 2018 GLC43, 1929 DB victory six sports roadster
Yes have hooked up scanner it came up intake camshaft sensor I’ve replaced it and scanner has no fault codes so only thing I can think of is injectors I took the injectors to a guy who tests them with high pressure machine but when he looked a one he said that they had oil in them and refused to put it in he’s machine and said that once there’s oil in them they should be replaced and that continuing to use them would eventually damage the engine I though he was saying that to try and sell me a new set of Bosch injectors thinking back he was probably right but can’t be sure that why I thought I’d try MB Forum does anyone have an idea of what it could be.
Thread Starter
Newbie
Joined: Dec 2025
Posts: 4
Likes: 2
ML63
i was hoping someone had had the same problem and could give me an answer…..still waiting maybe I might still get a response
Thread Starter
Newbie
Joined: Dec 2025
Posts: 4
Likes: 2
ML63
[QUOTE=Charlieml63;9246275]there was oil on them I thought the same thing was he having me on but apparently the fuel pumps work on oil pressure and one of them was leaking into where fuel travels through the line to injector rail and into the injector these were the only things I never replaced.
i was hoping someone had had the same problem and could give me an answer…..still waiting maybe I might still get a response
I’ve replaced both fuel pumps and waiting on 8 new Injectors to arrive
i was hoping someone had had the same problem and could give me an answer…..still waiting maybe I might still get a response
I’ve replaced both fuel pumps and waiting on 8 new Injectors to arrive
