Where should I get injectors and pump work? - Mercedes-Benz Forum
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post #1 of 25 (permalink) Old 06-08-2019, 10:21 AM Thread Starter
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Where should I get injectors and pump work?

Where should I get injectors, and which ones should I get? Where/who should I call for injection pump work? I have a non turbo 352 in an ex German army ambulance. I'd like to bump the power of course. My house is at 6,000 feet, and without a turbo, my cruising speed is pretty poor. At 2,500 RPM I can now do 51 MPH on flat ground. This is an improvement over the 43 due to the 395/85 tires I put on recently. It seems that I am either missing a cylinder, or my pump is not doing its job as of a week or two ago. So....I'm sure this has been discussed before, probably many times, but I didn't see it in an obvious location - how would I go about getting some HP through injectors and pump tuning? I think the truck sat for a long time before I got it, and I may have broke something loose driving it across country at 40 MPH, from Tampa, Florida to Bozeman, Montana. It did great the whole drive, but now it seems down on power. I put new fuel filters in it, cleaned the bowl, checked the air filter, changed the oil in the motor, tranny, diffs, and portals. Any input would be very much appreciated.

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post #2 of 25 (permalink) Old 06-08-2019, 10:34 AM
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At 6,000ft it will feel fairly anemic. But it should get 55-60MPH on flat ground. You want to look for the nearest Bosch truck shop. They can rebuild and test your injectors and or pump. To identify a missing cylinder you can use an IR gun and look at each exhaust port on the manifold. One will be very cool as compared to the others. That said, if it’s a hard miss you really should feel it beyond a little loss in power.

As an alternate, you can clean your injectors yourself but this disregards setting the pop off pressure and spray pattern. But a good cleaning may improve your spray pattern dramatically and fix your problem. Another option is to buy new nozzles and rebuild the injectors. This still disregards pop off pressure.

Anyways, this stuff is hard to diagnose via internet, but you really should check your fuel filters (all 3 of them) and update your primer pump before you start tearing things apart in search of sudden loss of power. You will likely find a ton of black flakes in your glass filter bowl. This can really kill the power on these things.
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post #3 of 25 (permalink) Old 06-08-2019, 10:38 AM Thread Starter
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I changed two filters (the ones on the front of the motor) and cleaned the bowl (full of what appeared to be rust). What is "updating the primer pump"?

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post #4 of 25 (permalink) Old 06-08-2019, 12:43 PM
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The original primer pump is all aluminum and has a whiteish plastic knob on it. These are prone to leaking both fuel and air. You want to replace it with the Bosch black plastic unit. They are cheap and work exceptionally well. They also do not require locking and unlocking to prime like the old stock ones.
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post #5 of 25 (permalink) Old 06-08-2019, 01:40 PM
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Best $22 (when I bought mine) improvement.

Primer Pump, New Style - BOSCH [0000908850] - $23.50 : Eurotruck Importers, Your source for Mercedes-Benz off-road vehicles and spare parts!

Doesn't leak, and is easy to use. Inexpensive. All love that .
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post #6 of 25 (permalink) Old 06-08-2019, 04:39 PM
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When (if) it comes to new injectors or nozzles, be aware Bosch Germany no longer makes the SBU nozzles - most comes from India and China. The quality is dubious in spite of the Bosch packaging. Ianunimog for instance had to go through 13 before finding 6 that performed to spec.

Life is like a sewer. What you get out of it, depends on what you put into it! - Tom Lehrer
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post #7 of 25 (permalink) Old 06-08-2019, 08:11 PM Thread Starter
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OK, so the primer pump you use when replacing filters to remove air?

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post #8 of 25 (permalink) Old 06-08-2019, 08:12 PM Thread Starter
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It's tough to get anything that is not Chinese junk anymore, it seems. Is there no aftermarket suppliers that make "high performance" injectors that work on 352's??

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post #9 of 25 (permalink) Old 06-08-2019, 09:00 PM
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Yes, that’s the primer.
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post #10 of 25 (permalink) Old 06-09-2019, 08:38 AM Thread Starter
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So, that primer pump will cause air leaks - that may cause fuel issues? Is that the theory? This has been shown to cause a "down on power" situation to others in the past?

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