300CE Fuel Pumps.

If the fuel pumps on my 300CE were failing what would my symptoms be?
Possible poor intermitent performance and occasional stall of the engine? Or are the pumps (I am told that there are 2) either good or bad and the car either runs or it doesn't?
Is there a way to check the performance of the pumps before replacement?
Fuel filter has been recently replaced.
Thanks Guys,

Julian.

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Julian.
88 300 CE
82 300 SD

[Benzmac]

If the pumps are noisy, and the problem is there, you should replace them anyway. The other thing is the over voltage relay. Replace it too. IF the pumps draw too many amps, it will kill the fuel pump relay .

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks for your reply.
No the fuel pumps are not noisy at this point in time.
Along side my idle problem the car has shut of a few times within the last month. This happens at a stop light etc. The car starts up right away each time. I am trying to link this problem to my ever niggling rough idle problem and the fuel pumps along with the over voltage relay have been mentioned.
I am looking for alternate oppinions before I go ahead and sink another 1k only to find that the rough idle / shutoff problem is still there.
Thanks for your help.

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Julian.
88 300 CE
82 300 SD

[bdrought]

May I be so bold as to make a suggestion? Techs can disagree with me if they like...

Electrics! Plain and simple.

Take every wire that goes to a ground point (brown wires to suspension turrets etc) Clean the contacts, sand the metal on the bolt, and reattatch. Then remove every sensor plug (coolant temp, air temp specifically) and clean the contacts. Remove the computer behind the battery, and carefully clean the contacts (careful not to damage it with static!). Replace the fuse on the overvoltage relay, and while yer at it, clean the relay contacts.

Put it all back together, and theres a very good chance the problem will have gone!

Bri

Put it all



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Brian Drought
1991 300CE
http://www.users.globalnet.co.uk/~drought/
ICQ: 2180069

JOOLZ1,

To determine if the fuel pumps have anything to do with your idle problem, test the fuel pressure at idle.

Good luck,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

[Arthur Dalton]

quote:

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Originally posted by bdrought:
May I be so bold as to make a suggestion? Techs can disagree with me if they like...

Electrics! Plain and simple.

Take every wire that goes to a ground point (brown wires to suspension turrets etc) Clean the contacts, sand the metal on the bolt, and reattatch. Then remove every sensor plug (coolant temp, air temp specifically) and clean the contacts. Remove the computer behind the battery, and carefully clean the contacts (careful not to damage it with static!). Replace the fuse on the overvoltage relay, and while yer at it, clean the relay contacts.

Put it all back together, and theres a very good chance the problem will have gone!

Bri

Put it all


Yes Sir. Wish I had a nickle for every part that gets replaced for a faulty connection.
Arthur

---

Thanks All.
I will be spending this coming weekend inspecting and cleaning all electronic connections, I see value in your opinions.
Are there any hidden wires / connectors that I should be looking for? What is the best method for cleaning sensor / computer / relay connections?
I will also be spending time to check the entire Vacuum system (based upon previous suggestions). I found a 1/8" severed hose between the Valve cover and some small cylinder by the intake housing. - Replaced this and noticed minor positive changes, will continue to check hoses. Anyone have any specific suggestions?
Brian - Thanks for your help, I am a Yorkshire descendant myself and have been here in California for 5 years. Miss the local Pubs and the Boddingtons. Hopefully you are enjoying your time in Milton Keynes.

Thanks all,
Will keep you informed on the Saga!

Julian.

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Julian.
88 300 CE
82 300 SD

All,
Thankyou for your inputs.
I will be spending this weekend checking and cleaning the electronics.
Are there any hard to find / important connections that I should keep my eye out for? What is the best way to clean the sensors and relay connections?
I will also be checking the vacuum system. I found a severed 1/8" line between the valve cover and some small cylinder type thing connected to the intake housing! - Replaced the hose and noticed minor yet positive changes.
Anyone have any tips on Vacuum line checks?
Thankyou for all your inputs.
Brian.--
I am from Yorkshire myself. Lived there for 20 Years and have spent the last 5 here in sunny California. I miss the Local pubs and the Boddingtons ale! Hopefully Milton Keynes is treating you well.- Thanks again

I will let you know the results of the weekend on Monday.

Julian.


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Julian.
88 300 CE
82 300 SD

After the weekend...
Not much time to do thorough troubleshooting or testing. Did notice that battery reads 11.8V cold and only 13V whilst the car is running. Bad alternator? Or something else?
Could this be attributed to idle problems?

Julian.
PS. Sorry for the previous double post.

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Julian.
88 300 CE
82 300 SD