How do I "jumper" the fuel pump relay to test it?

[86560SEL]

Can someone tell me how I "jumper" the fuel pump relay system to test it? OR tell me of another way to test the FP relay? The car is a 85' 380SE. I was told I could "jumper" it. Does that mean something like a paperclip connecting the electrical connections in there? Also, where in the fuse box is it located? There are several relays in there anyway.

I asked in that particular thread twice, but never got a response.

Thanks.

[cool]

whats your reason for testing the pump? whats wrong with the car? myabe thats one of the reason why no one is responding to your inquiry, second, its a very sensitive issue when it comes to fuel system, extreme caution should be taken when testing with these department. did you know that even if you have drained the fuel pump of its content it can still catch fire with a spark? due to the residue of gasoline.

[86560SEL]

Thanks. The reason why was designated in the original post, where it was recommended that it could be my FPR.

My car is often (but not always) "missing" when it initially shifts into 2nd to 3rd and 3rd to 4th gear- right when the RPMS slow back down. It does it 80% of the time... when hot or cold. Seems to be worse in cold weather (below 50°). When I first start it in the mornings and I just let it idle (starts at the touch of the key), it idles fine.... but if I "up" the RPMs a little, it will start missing/shaking and a couple of times it would "chug" for a few moment.

It also misses most of the time when it is idling in park or neutral. MPG's have went down from 21 mpg down to 14 mpg.

I have been told it could be:
fuel pump relay
vacuum leaks
idle control valve
manifold gaskets
OVP relay
temperature sensors
or:
fact that I have a bad thermostat (runs about 55-65°C on the freeway)

???? I really do not want to spend thousands on a 22 year old car with 270K.

BTW- the PO replaced the fuel pump 2 years ago.
Thanks.

[jhodg5ck]

@270K, your heads are Toast for one..

Also, if the cat is still on the car I'd wager it's quite clogged....amongst other issues prob. contributing to your issue.

To jumper your FPR, pins 7 & 8 on the female side of the relay will do it.. A piece of 14 gauge speaker wire works well.

Jonathan

[86560SEL]

Oh really? How lovely.

There seems to be plenty of "air" coming out the exhaust, from the amount of steam that comes out of the tailpipe when its cold out.

I guess I am used to hearing of MB's easily going well over 400K.

I have had Japanese cars with well over 300K and no problems with heads.

Oh well... perhaps its time to take it to the crusher.

Originally Posted by jhodg5ck

@270K, your heads are Toast for one..

Also, if the cat is still on the car I'd wager it's quite clogged....amongst other issues prob. contributing to your issue.

To jumper your FPR, pins 7 & 8 on the female side of the relay will do it.. A piece of 14 gauge speaker wire works well.

Jonathan

[jhodg5ck]

Any M116/117 valve guide is spent @ 200K..

MB designed the head w/ soft guides and hard valves. The valves will last indefinably, one just has to replace the guides every 200K or there about.

Air will still come out, just not as efficiently as it should..remember, this is just a big air pump.

Jonathan

[cool]

check your electrical system first for the shaking . check coil, ignition line, ignition rotor, high tension wire, spaark plugs, then to the fuel system.

[86560SEL]

Wow, what a list. Thanks. I will probably take it into the shop. When you say "check" those things... you mean "replace" right? Oh, I replaced the spark plugs about 2000 miles ago.

I guess I have not accepted a "worn out" engine, because even at this mileage, I still have NO oil leaks, OR no oil burning. It does not even go down at all on the oil stick between 3K oil changes. In fact, I have 3300 miles on the current oil and its on the same spot it was on when I changed it at 265,000. (It has 268,300 now). I currently have it on the "auto-RX" treatment interval- which I started 250 miles ago. Engine is quieter anyway.

[86560SEL]

Originally Posted by cool

check your electrical system first for the shaking . check coil, ignition lines, ignition rotor, high tension wire, spark plug, then to the fuel systems.

When you say "check" those things... you mean "replace" right?
I replaced the plugs 2000 miles ago.

Would a vacuum leak cause it to miss the way I described? I am thinking that the answer would be "yes".

Thanks.

[just-n-time]

You say you do not use any oil at 3000 change? how about water use?
That engine sounds pretty tight,if you are not showing oil lose at all then I would tend to think that the valve guides are still in good shape.My 420 used a half quart in 3000 so I am looking at guides and seals for the same. Water use can tell another story,if you have to add is it a leak up front or no noticeable leak,one is obvious and the other maybe internal lose and thus steam at the exhaust,If the later then you are going to have to do heads,it could be as simple as a head gasket. The next thing I would look at is The exhaust system clogged cat will cause a slowing of the speed and poor fuel mileage,unhook the system and see if it improves at idle, the next is the EHA,check to see if it is reading in spec,lots of post on it,The HEAT must go do not let it build change the thermostat and flush the core to help the flow, let us know how you are doin JNT

[86560SEL]

Thanks. Well, I just came in from being out at the car, checking connections, listening for "air leaks", etc. My air filter does look abit dirty, so I am going to change that this evening. That may be part of my lower MPG's I have been experiencing as of late.

That is correct- absolutely NO oil leaks or usage. I just checked the oil level again and it is still on the "full" mark on the stick @ 3500 miles. Water usage... hmm. No, I had not added any, but there are times when I cannot see any in the reservoir. I loosened the cap and some came into the bottom, so I am assuming its not that low.

I am not that mechanically inclined when it comes to these things, so I may be better suited taking the car to a local MB repair shop and see if they can work some magic w/o charging me an arm and a leg. Seems like it can be a # of differnt thing(s).

I was really needing the car to be in perfect working order by next Saturday, as I was needing to go on a fairly longer trip to do some training on a new computer system we are getting at work and wanted to take it to keep the miles down on my truck, but it looks like I will have no choice but to take the truck. I do not want to break down.

Thanks again!