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'86 190E 2.3 8vlv
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Discussion Starter #1
I (actually my 86 190E 2.3 8vlv) was having intermittant starting trouble. The problem turned out to be in the fuel pump relay.

I found out that they can be repaired. I opened it up, and sure enough, there was a crack in one of the solder joints. I re-soldered it, resealed the cover with silicone, and now it starts fine.

Remaining concern...the circuit board has turned black under the coil where the joint broke. This means that either it is designed poorly to handle the heat, or that there is a problem, either in the relay or elsewhere in the car, which means that it may blow again.

If the root problem is elsewhere in the car, I guess it is better to blow this one again than a new one.

If anyone has experience with this, I'd like to know.

I'll try to post pictures...

Can you see the blackened area on the circuit board and the broken solder joint?
 

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'86 190E 2.3 8vlv
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Discussion Starter #2
Figured it out, thanks to my brother (MB mechanic).

He said that the relay was being overworked because the fuel filter is probably clogged, so the pump and relay stay on longer, building up heat in the relay.

It all seems obvious now.
 

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86 190E 2.3-16V Euro
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thanks for that info. i had the same issue before. i think ill open up my old relay and take a look over
 

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'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
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2,186 Posts
joebob2 - 4/27/2005 10:42 AM

Figured it out, thanks to my brother (MB mechanic).

He said that the relay was being overworked because the fuel filter is probably clogged, so the pump and relay stay on longer, building up heat in the relay.

It all seems obvious now.
Although it might be time for your fuel filter to be replaced,(every 60,000 miles), the fuel pump is always running when the engine is running, therefore, the relay stays operated due to the design of the Continuous Injection System. You probably had a cold/bad solder joint causing a poor connection and a visible sign of heat damage on the circuit board.
You did a great job of isolating and fixing the problem and thanks for sharing your information.

Dave
 

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'86 190E 2.3 8vlv
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Discussion Starter #5
slk230red - 4/27/2005 10:14 AM

...the fuel pump is always running when the engine is running, therefore, the relay stays operated due to the design of the Continuous Injection System.

Dave
Dave-

You make a good point about the relay being on all the time anyway. Does a relay draw the same current no matter the current draw on the pump (relay current is either on or off only)?

If so, you are 100% correct.

Thanks,

Joe
 

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'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
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joebob2 - 4/27/2005 9:59 PM

slk230red - 4/27/2005 10:14 AM

...the fuel pump is always running when the engine is running, therefore, the relay stays operated due to the design of the Continuous Injection System.

Dave
Dave-

You make a good point about the relay being on all the time anyway. Does a relay draw the same current no matter the current draw on the pump (relay current is either on or off only)?


If so, you are 100% correct.

Thanks,

Joe
Yes, the current draw on the relay is the windings. The current draw on the relay would change only if there was a short in the windings. It there was an open, the relay would not operate...due to the lack of a magnetic field.

Dave
 

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I have 190e 16v 1986: fuel pump relay 002 545 36 05.
I removed the relay and I noticed the same burn marks. However, the circuit board for the 16v is entirely different. How would I troubleshoot this circuit board to ensure it is operating properly? Where would I get a Schematic for this relay. I've checked several web sites on the cost of one of these relays. Currently, I do not want to invest $224 for one of these relays. Looking for help.
 

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1992 190E 2.6L
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jduran - 5/4/2005 12:26 PM

I have 190e 16v 1986: fuel pump relay 002 545 36 05.
I removed the relay and I noticed the same burn marks. However, the circuit board for the 16v is entirely different. How would I troubleshoot this circuit board to ensure it is operating properly? Where would I get a Schematic for this relay. I've checked several web sites on the cost of one of these relays. Currently, I do not want to invest $224 for one of these relays. Looking for help.
If you look at the last picture above, see where the pen tip is pointing at a solder connection? That's a cold solder joint as the solder connection has deteriorated to the point where it no longer makes contact. Resoldering any such cold solder joints should take care of it.

--
d a v e

(who knows little about cars and a lot more about electronics repairs)
 

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'86 190E 2.3 8vlv
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Discussion Starter #9
jduran - 5/4/2005 10:26 AM

Currently, I do not want to invest $224 for one of these relays. Looking for help.
1. As demmons says, look at the board for either a cracked solder joint or if you don't see one, look for a circuit component that has popped or looks burnt.

If you don't find anything unusual, you may still bring it to a Radio Shack, and the nice people there (if it's quiet), may look at it for you.

If you can find the problem, they might tell you about soldering if you don't know already. It's not hard, but not easy to describe in words.

2. If worse comes to worse, check Autohausaz.com. They had one for the 8vlv for ~$53 + deposit.

Good luck , and let us know how it comes out...or post pics.

Joe
 
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