Author Topic: Injection pump and fuel injectors  (Read 1606 times)

mauro12

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Injection pump and fuel injectors
« on: May 28, 2019, 11:00:02 »
Hello guys, I wanted to ask you a question regarding fuel injection pump and fuel injectors. How do you know if the car needs an injection pump overhaul rather than new fuel injectors? My car has a rich mixture and a poor gas mileage ( about 14mpg) . Im thinking to buy 6 brand new injectors in the hope to solve the problem but at the same time I’m scared that my injection pump has to be calibrated . I would like to spend the right money for the right think.
Any suggestion ? Thank you
Mauro Pisani
250sl 1967 5speed zf manual

ja17

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Re: Injection pump and fuel injectors
« Reply #1 on: May 28, 2019, 15:33:06 »
Hello Mauro,

 It's difficult to guess what issues you have without analyzing the whole situation. Does the oil level in your IP continue to rise? Have you done the "linkage tour". You can have your injectors tested and possibly cleaned. Have you checked the fuel mixture with a meter or the "split linkage test"?
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

MikeSimon

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Re: Injection pump and fuel injectors
« Reply #2 on: May 28, 2019, 16:19:40 »
I am not sure that your problem can be blamed on the injectors. These are not "unit injectors", they are just nozzles. They can be plugged or they can drizzle, and can cause poor performance and response but I don't think they would be the cause of poor fuel mileage or a rich-running condition.
1970/71 280SL Automatic
Sandy Beige
Parchment Leather
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German specs
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mauro12

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Re: Injection pump and fuel injectors
« Reply #3 on: May 28, 2019, 17:14:44 »
My fuel injection pump is the r22 model with no oil reservoir ( probably installed from the previous owner). Has always worked fine with normal fuel consumption and emission within the limits. Some years ago i started to have some rich mixture conditions with black smoke in acceleration and a slow increase of rpm. This problem was partially solved with a full cleaning of the injectors, power of the car now is ok with good acceleration . The only thing i cannot figure out is the high fuel consumption but im convinced that is a mix between wrong calibration of the pump ( probably worn out parts) and a not perfect spray pattern of the injectors. What's the average cost of a complete service on our inj pump?
The ignition of the car is ok as the linkages and i recently had a full service of the throttle body.
Mauro Pisani
250sl 1967 5speed zf manual

Shvegel

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Re: Injection pump and fuel injectors
« Reply #4 on: June 07, 2019, 11:20:50 »
Last number I heard from Hans at H and R was $1750 for the pump, check injectors and cold start injector.  Speaking of that start the car and remove the tiny hex bolt from the side of the cold start injector.  If fuel leaks out it needs repair or replacement.

Cees Klumper

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Re: Injection pump and fuel injectors
« Reply #5 on: June 07, 2019, 11:44:48 »
I also think it might be something relatively simple, such as a worn barometric compensator or the cold start valve leaking. I just recall experiences of members who had their pump overhauled, only to find the actual problem was elsewhere. So it's worthwhile to check the other possibilities first. There are of course reputable rebuilders in Europe, probably referenced in other threads here.
Cees Klumper
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Shvegel

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Re: Injection pump and fuel injectors
« Reply #6 on: June 07, 2019, 14:51:33 »
I didn’t spend a ton of time around Hans but I did hear him on the phone telling a number of people they didn’t need him. Having rebuilt my own pump I can tell you the way they are built it is nearly impossible for it to slip out of calibration. 

Benz Dr.

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Re: Injection pump and fuel injectors
« Reply #7 on: June 07, 2019, 15:23:48 »
I find that pumps tend to go rich over a long period of use. This might be fuel injectors or leaking cold start valve or the pump. So, it may not go out of calibration, but small amounts of wear can affect how they work seeing how they're very sensitive to any kind of adjustments.
« Last Edit: July 01, 2019, 20:17:19 by Benz Dr. »
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mauro12

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Re: Injection pump and fuel injectors
« Reply #8 on: June 09, 2019, 11:50:06 »
My CO at idle is around 9%, so is by far too high. Consumption about 14mpg. The csv is ok and linkage too. I don’t know if to buy 6 new injectors and maybe solve the problem or send the pump  and injectors to a specialist and have them cleaned and calibrated. Would be a pity to buy new injectors and instead I could gain the same result with a good ultrasonic cleaning process.
Mauro Pisani
250sl 1967 5speed zf manual

Derm Cain

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Re: Injection pump and fuel injectors
« Reply #9 on: July 01, 2019, 05:08:54 »
Had issues with my pump last year.  I have been around at lot of, mostly fuel injection, test benches and experienced people over the years.  H&R (Hans) has a great facility and knowledge.  Excellent service and reasonable pricing. 

lowpad

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Re: Injection pump and fuel injectors
« Reply #10 on: July 01, 2019, 22:05:36 »
I don’t believe that Hans is involved with H&R anymore. I’ve dealt with Marty Neubauer there.  He has extensive testing equipment and helped me with my cold start injector.  He’s all set up to test injectors.  You can reach him via FB. 
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Benz Dr.

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Re: Injection pump and fuel injectors
« Reply #11 on: July 01, 2019, 22:52:56 »
I don’t believe that Hans is involved with H&R anymore. I’ve dealt with Marty Neubauer there.  He has extensive testing equipment and helped me with my cold start injector.  He’s all set up to test injectors.  You can reach him via FB.


Hans went to the great injection pump in the sky a while back. I believe Marty is his step son.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

lowpad

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Re: Injection pump and fuel injectors
« Reply #12 on: July 02, 2019, 23:13:42 »
When I was there a few months ago, he was busy as heck, which is encouraging for such a specialized business.  Apparently Hans left him an attic full of pumps ...
1966 230SL (6/66 build)
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158 Exterior / 040 Hardtop

perry113

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Re: Injection pump and fuel injectors
« Reply #13 on: July 06, 2019, 15:12:43 »
I just had my injection pump rebuilt on my barnfind 1966 230SL 4 speed. I sent it to Robert Fairchield. He fully serviced the pump and checked the injectors and cold start valve and solenoid.
I also had him rebuild my 1965 230SL automatic and 1963 220SEB coupe's injection pumps. No issues whatsoever.
His work and pricing are very good but at the expense of a somewhat long turnaround time.
I would say his pricing is half of what the handful of other other specialists are.
Peter Perry
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Shvegel

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Re: Injection pump and fuel injectors
« Reply #14 on: July 08, 2019, 01:55:36 »
After I rebuilt my pump I had Hans run it on the dyno and set it up for me.  Once I showed him how interested I was in the pumps the gates opened and he took me on a tour of the shop.  Besides the average everyday stuff he had quite a valuable array of pumps on the shelf for sale.  Early 911's, BMW 2002 pumps and even 2 300SL pumps.  Even at his advanced age and frail condition he was very excited about sharing what he knew. 

mauro12

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Re: Injection pump and fuel injectors
« Reply #15 on: August 01, 2020, 14:31:22 »
Hello guys, probably this September I will convince myself and get my injection pump to overhaul . The car is running great but I want to get rid of this rich running condition and poor fuel mileage. My doubts are regarding the expression : never fix something that isn’t broken and my pump seems to work. I’m pretty sure the wrd is not working well. Probably the injection pump thermostat is still the original one and maybe is broken. I read that to fit the new thermostat you have to drill some holes is it right? The new thermostat is slightly bigger than the old one.
What do you think is an onest price to have a calibration and overhaul of the pump? Thank you
Mauro Pisani
250sl 1967 5speed zf manual

Peter h

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Re: Injection pump and fuel injectors
« Reply #16 on: August 01, 2020, 15:41:06 »
I would not look at the price first, but whether the result is perfect.

From 1500 euros upwards you have to calculate.

Peter
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mauro12

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Re: Injection pump and fuel injectors
« Reply #17 on: August 01, 2020, 16:01:37 »
Yes of course , I just wanted to have an idea. Have you gone trough this process ?
Mauro Pisani
250sl 1967 5speed zf manual

Taleb

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Re: Injection pump and fuel injectors
« Reply #18 on: August 01, 2020, 20:26:26 »
don't waist your time , send it to marty from  H&R for complete restoration will cost you 1700$ I just did my two pumps R20 and R14 ,,,, good luck

mauro12

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Re: Injection pump and fuel injectors
« Reply #19 on: August 01, 2020, 20:34:40 »
I found here a local bosch service that has the right equipment to overhaul the pump .i think the difference must be amazing with the pump perfectly calibrated right ?
Mauro Pisani
250sl 1967 5speed zf manual