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Fuel Management

Hot start problems - a solution.
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... now having read my own reply, the original pump is wonderful and will deliver for many years. Just be prepared to replace the item as soon as you suffer hot start problems. It is another expensive consumable. I moved to the Bosch 044 as, at the time in my part of the world, new pumps were hugely expensive & scarce, and rebuilt pumps were not terribly reliable.

regards
Michael Davies
Looks like a Bosch 044, which I went to >15 years ago ago to overcome the hot start and vapour lock problems. Easy fit if you use a w108 pump mount, but rather noisy.
The 044 pump is high volume low pressure for racing and hot rods.
Mine has now started cavitating and needs replacement, so I have cold start problems due to low pressure and mid-range full throttle misfires due to starvation.
Please note that the market is now flooded with nasty 044 fakes. Please either purchase from Bosch motorsport direct or from a very reputable shop-front business where you can eyeball the pump, as I just suffered a 'bait and switch' internet purchase for a 'genuine' pump. The photo was of a genuine pump. There is LOTS of literature online for spotting a fake, but honestly, the time and effort to replace the pump is greater than any perceived saving - given the fake will fail and may never deliver correct pressure. The simple reality is that there is no premium pump at 1/3 the full price. Bosch has now added a hologram and unique validation code to the box label to combat the fraud.
Really.

regards
Michael Davies
Would you please share the brand,model and specifications?
Thanks

jim


Jens

1964 600 SWB W100 #099

1965 600 SWB W100 #141

1967 600 SWB W100 #867

1971 C3 Corvette 454

For some reason I experienced a hard start problem on two 600 at the same time.

One of them also had a high idle after warm up - that was the warm up thermostat not working letting excess air raise the idle.

With some feedback from StarMotors I checked fuel pressure at the return valves. Both engines had about 0.6 bar of fuel pressure instead of the needed 1.1 bar.

Engines could be started with the aid of spray can start help (or what ever you call it :-). ) and run normal.

I did try to switch the long style pump to another one, but still had low pressure.

Eventually I installed a modern in line pump with custom fittings to fit the original hoses.

Result: 1.1 bar pressure at the cold start valves and hot start problems gone on both cars.

No matter what pump you decide to use just make sure the pressure is correct.

Just my 10 cents.....


Jens
1964 600 SWB W100 #099
1965 600 SWB W100 #141
1967 600 SWB W100 #867
1971 C3 Corvette 454
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