Fuel Injector Pump problem

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thirstymerc
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Fuel Injector Pump problem

Post by thirstymerc » Mon 12 May, 2008 6:45 pm

Hi all,

I have been having some issues with my cold starts on the old 108.

It has got to the point where it takes a few gos for the engine to finally kick over and then I have to leave it for 5 minutes to warm up until I have enough power to drive off.

I believe it is the fuel injector pump which would make sense and explain the problem as the engine itself seems fine.

Before i throw in the towel and have to get the whole pump replaced, a very wise merc owner suggest I try one thing before I consider a rebuild.

I was told that the pump might not actully be stuffed, but that towards the back of the pump there is a temperature compensator connected into the cooling system. The sensor is a position thermostat that extends as it gets hot. This sometimes leaks coolant, and this coolant will gradually seize the plunger of the cold start mechanism. It will seize into the 'warm' position, as the plunger extending has a stronger push than the return spring.

All that is necessary to fix it is to remove the cold start compensator and free up the plunger underneath the cold start tower and to make sure all the relevant shims are replaced where they came from and all will be well.

Before I have a good look at it this weekend and attempt to look at the problem, I was wondering if anyone else has ever attepmted this and had some advice?

I would be interested if anyone else has had the same problem?

:?
Steve
1971 VW Beetle - Barry the Bug
1969 280se w108 - Max the Merc
1971 250 w114 - Molly the Merc

hands_aus
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Re: Fuel Injector Pump problem

Post by hands_aus » Mon 12 May, 2008 10:15 pm

Does the 69 280SE have a 6 inline fuel injection pump with 6 outlet pipes like the attached pic?
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Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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thirstymerc
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Re: Fuel Injector Pump problem

Post by thirstymerc » Tue 13 May, 2008 9:30 am

Hi Bob,

I believe so from memory.

Have you had experience with fixing this problem?

Steve
Steve
1971 VW Beetle - Barry the Bug
1969 280se w108 - Max the Merc
1971 250 w114 - Molly the Merc

hands_aus
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Re: Fuel Injector Pump problem

Post by hands_aus » Tue 13 May, 2008 9:16 pm

the International Internet Pagoda group has various "TOURS" one is about the Injection pump.
Look here http://www.sl113.org/forums/topic.asp?A ... PIC_ID=790
The valve system you are enquiring about is called the WARM RUNNING DEVICE. (WRD)
I have removed the thermostat housing and freed up the aluminium valve. The housing is aluminium also and they can bind. Grooves can form in the side of the valve.
There are pictures attached which show the Injection pump in various stages of disassembly.

The thermostat can become LAZY as it gets old. This means that it will not extend fully and the valve will not shut off the additional air supply when up to normal temperature.
IPAirSlideValve_2.JPG
IPWarmUpDevice.jpg
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Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

hands_aus
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Re: Fuel Injector Pump problem

Post by hands_aus » Tue 13 May, 2008 9:36 pm

here are a couple of additional pics. one shows the inside of the housing with the valve still inside.

When the Injection PumpThermostat housing is removed there is a spacer ring between the upper and lower parts.

see the pics.

The thermostat is relatively cheap to replace. If you decide to replace it be aware that the new one might be slightly different to the original one.
I had to drill out the spacer ring to allow the thermostat to sit flat.
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Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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thirstymerc
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Re: Fuel Injector Pump problem

Post by thirstymerc » Wed 14 May, 2008 9:53 am

Thats great thanks Bob. Exactly what I wanted to know and the images will be a terrific help.

Hopefully this will fix my problem and I don't have to replace the whole pump.

I will keep you posted!

Steve
Steve
1971 VW Beetle - Barry the Bug
1969 280se w108 - Max the Merc
1971 250 w114 - Molly the Merc

hands_aus
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Re: Fuel Injector Pump problem

Post by hands_aus » Wed 14 May, 2008 11:25 am

Hey Steve,
You can always have it rebuilt. There is a crowd in Melbourne who do the work called *Morassi and Williams. They will be in the phone book. I spoke to them about 5 years ago and they seemed knowledgeable. I can't recommend them workwise as I have not used them, yet.
Replacing the pump should be the absolute last thing. $$$$$$$$$$$$$$$$$$
Pumps are extremely reliable but given yours is 40 odd years old some maintenance is necessary.
* edited

There should be 3 shims under the housing where it sits on the Inj pump body.
Keep in mind that the shims can be removed individually to adjust the overall fuel / air mixture. So if you have less than 3 shims don't worry. The shims were also of different thicknesses too.

I learnt how to adjust my Pagoda air/fuel mixture to get optimum performance.
One of the big issues with the old cars that have mechanical injection pumps is that the cup ends of the linkage rods wear and then everything goes out of tune.
The best thing you could do is to eliminate any sort of play (longitudinal and rotational) in the linkage rods.
Make sure the inside of the inlet manifold is clean and that the venturi valve is closing.
On the injection pump is a small air filter. It takes a 22mm open end spanner to remove it. They can become blocked and then reduce the additional air supplied during warm up. You can blow through these filters as a check. They are available new.
Also check that the CSV cold start valve is not leaking. MB says more than 3 drops a minute and the CSV is leaking.

I have added a pic showing the air filter
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Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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drew56cus
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Re: Fuel Injector Pump problem

Post by drew56cus » Wed 14 May, 2008 1:28 pm

Sorry to butt in on this post, but gee Bob, judging from the photos, you have such young hands for a man in the massage industry! Do you use anti-ageing cream for lube??
Ha ha, Drew
Drew
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Re: Fuel Injector Pump problem

Post by hands_aus » Wed 14 May, 2008 7:51 pm

Hey Drew,
errr, ummm, ahh, oh ohh, caught out!!!!! :oops:
I borrowed some pics, you know how it is :lol:
I use whatever it takes.
My massage oil is great stuff but not quite the elixir of life,
maybe i need to wash the axle grease off my hands, they do look puffy, :lol:
Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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thirstymerc
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Re: Fuel Injector Pump problem

Post by thirstymerc » Wed 21 May, 2008 12:19 pm

Hi guys,

I had a quick look at the cold start tower last night. I will be taking it out completely this weekend.

Just wondering how much liquid/coolant is expected to come out when I disconnect the coolant hoses?

I attempted to disconnect the top hose last night to quite a flow of fluid.

Is this just excess fluid or do these hoses need to be clamped after being disconnected?

Thanks again!

Steve
Steve
1971 VW Beetle - Barry the Bug
1969 280se w108 - Max the Merc
1971 250 w114 - Molly the Merc

hands_aus
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Re: Fuel Injector Pump problem

Post by hands_aus » Wed 21 May, 2008 9:26 pm

When I dismantle the WRD on my Pagoda I don't remove the hoses.
They only need to be removed if you are going to replace/remove the injection pump thermostat.

You may want to take the opportunity to flush the cooling system.
Alternately just do this job and learn about this aspect of the injection pump and do the cooling system later.

If you MUST remove the hoses, remove the radiator cap to relieve the engine cooling system pressure.
You can also disconnect the lower radiator hose and let some coolant out.

I just undo the 2 thermostat housing screws and carefully lift it up out of the way.
Then undo the bottom 2 screws that hold the VALVE housing to the injection pump body.
The SHIMS will be under that housing.

Can I suggest that you spray the 2 sets of screws with some penetrating oil an let it soak in.

When re-assembling the WRD make sure that no coolant gets into the lower valve housing.

I actually add a few drops of engine oil every 6 months when I do a grease and oil change.
I also push the plunger up and down a couple of times to make sure it is moving freely.

hope this is helpful
Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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thirstymerc
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Re: Fuel Injector Pump problem

Post by thirstymerc » Thu 22 May, 2008 10:17 am

Thanks Bob,

That is exactly what I needed to know as I was hoping I didn't have to remove the hoses for this job.

I might leave the flush till the next little project, but I am having fun poking my way around the odd jobs under the bonnet.

I really appreciate your unending knowledge!

Cheers

Steve
Steve
1971 VW Beetle - Barry the Bug
1969 280se w108 - Max the Merc
1971 250 w114 - Molly the Merc

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Kiwi108
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Re: Fuel Injector Pump problem

Post by Kiwi108 » Thu 22 May, 2008 10:39 am

Here an interesting diagram of the cold runing enrichment mechanism
kugel9ze.jpg
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Darryl from Kiwiland

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Re: Fuel Injector Pump problem

Post by hands_aus » Thu 22 May, 2008 8:24 pm

Steve,

I don't know if you went to the Pagoda site I posted earlier but it has lots of discussion about the WRD and cold start issues.
Also there is an INJECTION PUMP TOUR that you can 'search' for.
The site is free to use and you can 'search' without having to establish a username.

The Pagodas have a lot in common with the finnies eg, suspension, steering, transmissons, and also in common with the early 108's.

One point to remember about the WRD valve and housing is that they are both aluminium and both could be scored. This will have to be removed very carefully because you don't want to allow air past the valve.

When you have finished cleaning and lubing and re-assembling the valve you can test that it is working properly by removing the air filter and putting your finger over the opening to feel if there is suction of air.
Gradually as the engine warms up the amount of additional air being taken in will decrease to zero.
If you listen you will hear this happening. You can use a length of plastic tubing like a stethoscope.
It is not uncommon for the valve to not fully shut off the additional air.
Feel the hole and there SHOULD be little or no suction.
Bob Smith
Brisbane

1967 'early' 250SL, auto, PS

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Aegean
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Re: Fuel Injector Pump problem

Post by Aegean » Tue 10 Jun, 2008 5:34 am

hands_aus wrote:Hey Steve,
There is a crowd in Melbourne who do the work called Morassy and Williams. They will be in the phone book. I spoke to them about 5 years ago and they seemed knowledgeable. I can't recommend them workwise as I have not used them, yet.
I can recommend them. They rebuilt my 6.3 pump. It is MORASSI, not Morassy, if you are looking for them in the phone book.

Craig
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Re: Fuel Injector Pump problem

Post by berntd » Thu 21 Jan, 2010 2:01 pm

Hello

As one who has owned and had problems with all these cars, may I suggest that your problem could also be related to the actual cold start valve and/or its thermoswitch.

The thermoswitch often burns out an then the cold start valve pisses fuel into the intake maifold.
The cold start valves also start leaking or get seized and do the same thing.

Have you tested the switch and valve?
The switch needs to give you a ~1 second (from memory) 12V pulse onto the cold start valve when the engine is cold. Much shorter to none if warm. there is a simple procedure to test the cold start valve operation.

Kind regards
Bernt

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Re: Fuel Injector Pump problem

Post by Ivanerrol » Thu 21 Jan, 2010 2:36 pm

There's this one on stealbay at the moment.

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... K:MEWAX:IT

You could always call the seller and ask it's condition - the telephone number is on the listing.
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Re: Fuel Injector Pump problem

Post by wbain » Wed 23 Apr, 2014 6:51 am

IMHO, these injection pumps are analog(ue) computers.
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