300ce twin fuel pumps

[ricky300ce]

Hi replaced both fuel pumps on my 300ce 24v but pumps are slightly bigger and when both pumps are connected car cuts out do you think it is over fueling starts first time and runs fine on one pump was thinking of changeing it to single pump of an sl 129 any suggestions thanks

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[stwat]

Are you sure you bought the correct pumps? And if they are bigger, how did you manage to fit them in to the fuel pump bracket? Did you change the filter at the same time? if so, is it fitted the right way round?

 

[carat 3.6]

One pump will not supply enough fuel for that engine, it will idle but may struggle further up the revs.

As above, are you sure everything is connected correctly?

 

[ricky300ce]

The fuel pumps were after market so slightly wider so the fuel filter does not fit it's smaller do you think the fuel filter could be to small I put it in the same way the old one came out I've still got one of the original pumps wich I tested wich I tested and works perfectly , I should just get another original pump it just bothers me why as soon as take the cable of the pump it runs ok I did replace the electrical connectors at the the pump ends , but have also looked at different pictures online and seen the filter the other way round



This going to sound stupid but this the way my filter is but is my 3rd one but the first one was faceing the other way ?

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[ricky300ce]

Just thought as sl129 3.0 works on single would easier but my engine is the 300ce 24v



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[ricky300ce]

Also I no I'm asking a lot but the rev counter and oil pressure gauge are not working I'm just trying to get it in at least a half descent running state before i have most of the engine parts replaced thanks for your help

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[ray_hennig]

The fuel pumps were after market
View attachment 47385

I did that once. They leaked as well. Put proper ones in a week later and all was well.

RayH

 

[carat 3.6]

I should just get another original pump it just bothers me why as soon as take the cable of the pump it runs ok I did replace the electrical connectors at the the pump ends

Are sure you have'nt wired one of the pumps to run backwards? The 3.0 r129 runs the same twin fuel pump setup you have.

 

[jaymanek]

Even if they are slightly bigger or more powerful I cant understand what difference it would make.. The fuel distributor just sends the extra fuel back down the return.

Have you blown the OVP relay maybe?

I would get an original set of pumps used... Not cheap but they hardly ever go wrong.

 

[grober]

flow as per diagram-- the direction of flow through the filter should be marked with an arrow somewhere on the body. The smallest unit to the right of the picture is the fuel accumulator which is basically a spring loaded diaphragm. Its purpose is to maintain fuel pressure in the system in the short term after switch off to assist restarting.

 

[ricky300ce]

Thanks I did replace ovp and the maf will double check flow and wireing and have just ordered another pump thanks the ovp relay came with a different part number would that make a difference the car starts alright with the two but cuts out but the priming noise stays until it cuts out so maybe it is the wires I will no by the end of today cheers

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[grober]

The fuel pump relay [FPR] is a 2 stage affair. First it primes the system for starting- that's what you hear on switching on - the pumps run to pressurise the system. When the engine cranks over the FPR has to receive a signal that the engine is running/turning over to switch to its second mode= continuous electrical supply to the pump- its a safety feature to stop the pump running if the engine was to stop unexpectedly as in a crash for example. Certainly worth checking replacing the FPR and whether its receiving an engine running signal-- which might be OVP related -- as below IRRC in early cars the cars received a signal from the instrument cluster---beside rev counter? as to whether the engine was running-- later cars from the engine ECU.

 

[balge]

OVP on my 300TD failed a few weeks back - symptoms included no tacho or pressure gauge...

 

[ricky300ce]

Have changed ovp still same problem still no oil pressure or speedo is there any other relays for this cheers

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[grober]

Suggest you next step might be to check the instrument cluster itself for damage or water ingress. There is also a big earth bolt on the bulkhead in behind there also. You can make up 2 removal tools from a wire coat hanger.
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