fuel delivery problem - Page 7 - Alfa Romeo Bulletin Board & Forums

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post #91 of 97 (permalink) Old 04-04-2005, 04:41 AM
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Originally Posted by slyalfa
BTW what do you think the new(not so new) Bosch Gasoline Direct Injection system is.
put some control in a pump like the spica and put the injectors in the head.
That is not what Bosch's DI is- they have a pump that changes the fuel pressure from about 40psi to 50-100 bar. The injectors are still electronically controlled.

And EFI inejctors are not as bad as you think- the 140psi is only a reasonable advantage for about a minute from a 70 deg start. After that, most of what comes out of an electronic injector is vapor, or vaporizes instantly on the back of the intake valve. I've seen some really cool videos showing this, on 10 year old injectors- newer ones are really good at the cold start.

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post #92 of 97 (permalink) Old 04-05-2005, 02:06 AM
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hmm I must have looking at one of the older ones then. bosh has been doing DI off and on sence the 1950s
I will have to see what there are doing. a quick google search showed the VAG system that is like the spica but with one plunger and that goes to a selector I did not see how the selctor worked.

So here is a simple test. take a spica pump and mistime it, does the car run better or worse?
Now look at the EFI injectors most run close to 95% on time at WOT that it like the spica out of time. And the that does not even count for the 2nd added benifet of the hi PSI.

Not only does the spica inject all the gas while the valve is open it also ramps the flow up and down matching the air flow. The air being sucked in with the big pistion and the gas being pushed in with the small one both on crankshafts.
some of the new DI parts might be good as a replacment but the spica has a lot going for it it just needs some control.

Also I was thinking the rack movment speeds will be a lot slower in real life due to the fact that we can not go from say 1000RPM to 8000RPM in a instant. The fastest change will be the stomping on the gas and leting up like for a shift and that is not that fast . It might be fun to wire it up and log as it is now and see how fast it moves now. it would also be a good way to dump the current 3dcam info into a file as a starting point for when the rack is controled. but that can be bult on the fly with the WBO² but it still would be good to have a starting point at lest for the first one. It might be tricky fiting a pickup in ther with out affecting anything. Once the logic is removed there will be a ton of space but with every thing there it is kinda hard. it might be best to do it on a bench with the pully removed and geting the rack info from the pully side.
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post #93 of 97 (permalink) Old 04-16-2005, 10:22 AM Thread Starter
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I managed to get a spare spica pump for my Monti that is in good condition.

Have tested the various components and oiled the system, I installed it back in my Monti and guess what --- it started first time - on the first turn of the key.

Next steps are to see if I can get the car back in tune.

I tested the TA when it was off the car, it seems to be out of spec.

At 10c - 19mm
At 20c - 22mm
At 100c - 27mm

According to my monti manual, TA should be 23mm to 31mm....

At idle, I am running rich with smoky (black) exhaust and the plugs are sooty when removed.

Next job is to adjust the throttle linkages and the spica reference gap -- fingers crossed.

A few questions,

a) to influence the 'richness', I should work on the throttle linkages, spica reference gap and then FCS -- is this right ?
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post #94 of 97 (permalink) Old 04-16-2005, 05:54 PM
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Glad to hear you found a serviceable pump. Be sure to keep it well lubricated in the logic section and the filter clean in the pump section. Also, I strongly advise using Marvel Mystery Oil or some other upper cylinder lubricant in the petrol.

It sounds as if the TA is weak and leaking and causing an overrich mixture. The small piece of a Monty manual I have says the dummy TA is 29mm, so that would mean that the actual should extend 29mm at 175F. You can try using your present TA by getting the engine to 175F, then using the adjusting screw under the TA to set the pump gap between the reference screw and the throttle lever at .5mm clearance. If you run out of adjustment before you can get that gap, then you can either temporarily insert a small 2mm extension onto the TA or temporarily install a dummy TA. Using a dummy TA temporarily is ok . . . you just won't have the warmup enrichment.

As far as adjusting the mixture, that's the LAST thing that is done, and that is done exclusively with the FCS. The short version of tuning is:

1. Adjust throttle relay crank stops. Idle stop - crank perfectly level. Wide-open-thorttle - 73 deg from idle stop.
2. Adjust pump gap, rod disconnected. .05mm gap
3. First adjustment to throttle butterfly master throttle bores, then syncronize with others. All throttle plates should be exactly the same. The manuals show the use of a Uni-Syn throttle synchronizer. With the throttle relay crank sitting on the idle stop, the throttle butterflies should have only .03mm open . . . essentially "just" closed. ALL idle air is supplied by the idle air distributor on th back of the engine.
4. Adjust throttle rod (relay crank to injection pump throttle lever), engine at operating temperature, adjust rod so that a .5mm pump gap is retained.
5. With engine at operating temp, and all other adjustments done, adjust the screw on the idle air distributor to achieve an 800 rpm idle speed.
6. Adjust the FCS to achieve a good mixture. Plugs tan and clean, with just a very slight hesitation when you crack the throttle open suddenly.

Before you start changing and throttle synchronization or stop screws, check twice. Chances are they're ok where they are now. You may want to make a dummy TA to help with the tuning, or as a temporary replacement if you have to send yours out for a rebuild. There's a previous thread on the BB on how to make one out of a bolt, 2 nuts, and washer.

John Stewart
74 Spider
91 164S
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post #95 of 97 (permalink) Old 05-04-2005, 12:31 PM Thread Starter
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Just to close off of the original problem that started this thread.

The problem turned out to be a very badly broken spica pump. The cause of this
was basic lack of care to the oil filter in the 8cylinder montreal pump. I think it started to fail about 2 months ago when it became hard to start, one of the connecting rods that go around the crank of the pump had broken -- this made the pump very stiff to turn -- which probably accounts for the dramatic loss of power over the last 2 months.

I sourced a good replacement pump.

The car is now back running, starts on the first turn of the key, idle and revs nicely. Still need to take it for a good run to adjust the fuel/air mixture

Thanks to everyone who helped me and especially John S for the graphic tutorials

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post #96 of 97 (permalink) Old 05-04-2005, 03:37 PM
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Great job, Adian! Congrates.


Series 2 USA 1750 GTV (in Series 1 European clothing)
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post #97 of 97 (permalink) Old 03-01-2017, 02:09 PM
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Originally Posted by papajam View Post
Yes, a single L-Jet pump does work in the Monty. Have a friend who did just that a number of years ago and with no mods to the restrictor. Will try to get a pic of the installation this weekend.
I want to replace original pump because I have only one left, sb. before me threw the second one away. There are many L-jet pumps, aren't they? Can you please help me with choosing the right one?
Thank you!
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