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post #1 of 97 (permalink) Old 03-13-2005, 01:25 PM Thread Starter
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fuel delivery problem

Hi

I am having problem with my 72 Montreal. Recently it started from very bad hesitation when trying to drive in any gear.
The car will accelerate slowly to about 30kph but has very poor pickup
and will max out at 30/40 kph....

The car is slow to start but once started it idles smoothly at
750-800rpm

I took the plugs out today to see what I would find. On the right
cylider bank, the 1st and 2nd plugs are brown/greyish indicating a reasonable combustion. But the 3 and 4 plug (closest to the windscreen) are very
clean and dry --- almost like no fuel is getting to them. It appears
to be the same of the left hand cylinder bank with plug 7 clean and
dry.

To me it looks like I am not getting any fuel into 3,4 and 7 ... I
disconnected the metal injection line from the spica pump the cylinder
3 and 4 and found that they look very dry too !


Could it be that Spica pump is not delivering fuel to all 8 outlets ?

I have checked the following

- I have spark/ignition on all eight ignition leads
- throttle settings are reasonable (not perfect but ok)
- fuel filter in engine bay is new and clean
- oil filter in spica pump is new and clean
- spica fcs is set at 14 threads. (and the car ran ok like this previously)
- idling air channels are fine (new homemade o-rings installed by some
previous owner)

The car idles fine and revs fines in neutral ........

please help ! I have had the car 4 months and not been able to take it for a good run yet..........
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post #2 of 97 (permalink) Old 03-13-2005, 03:14 PM
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First of all, I've never even seen a Montreal in person, so I have no direct experience on the Alfa V8. The SPICA system, is functionally the same as the 4 cylinder models, so I'll take a stab at it.

Has it ever run well while you've owned it, or did you buy it broken?

I'm going to assume you're correct and that the ignition system is good. Also, has this car sat unused for a long period of time before this problem occurred?

The SPICA pump operates at about 350-400 psi, so something would have to be broken in the pump section of the injection pump for a particular cylinder not to get fuel in the fuel pipe.

Let's check the easy, non-invasive stuff first:

1. Are the fuel pipes in good condition and have not been kinked? Be carefull with those pipes. Don't bend them. There are no spares available except from salvage, and for Montreals, that means virtually nil available.

2. Disconnect the fuel pipe at the injector and crank the engine without starting it for about 15 seconds. (Disconnect coil wire) Any fuel at all coming out the fuel pipe? It won't be much since there's very little injected in each cycle. If no fuel at all, loosen the connection at the injection pump and see if there's any exiting the fuel tower on top the pump.

If really getting no fuel (compare to a good cylinder), then I might suspect that the plunger pinon has loosened and is not turning the plunger, thus allowing the variable displacement port to go to the fuel delivery mode. This sounds complicated but is really simple when you look at it. See the picture below. The toothed rack at the back moves forward and backwards (full forward being fuel cutoff). The pinons have a few teeth also and are turned slightly by the rack (which is connected to the throttle). These pinions pinch the plunger and thus turn the plunger to increased fuel delivery.

So to make a long story short, if the pinch screws are no longer pinching the plunger, then throttle movements aren't going to increase fuel delivery in those particular cylinder(s) affected.

I'm not saying that's what's wrong, but apart from a blocked fuel pipe, that's about the only thing that can affect fuel delivery in just a particular cylinder.

I suppose, but very very unlikely, there could be a fuel blockage in the injection pump internal fuel manifold in those particular cylinders.

If you think the pinions may be loose (again, very unlikely), you can remove the inspection plates on the side of the pump, cycle the throttle and look for the plunder shafts to move with the pinions and toothed rack. If they don't, then the pump needs to be sent back to Wes Ingram for a re-calibration. It is completely impossible to reset the pinions without a dedicated test bench and the knowledge on how to do it.

The picture below give you an idea of what I'm talking about. Note that this is a 4c pump, but the Montreal pump is functionally the same.
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post #3 of 97 (permalink) Old 03-13-2005, 03:42 PM Thread Starter
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Hi

The car ran well for the first two months but was idle for a long period (1-2 yrs) before that.

It had the fuel filters in the tank and engine bay replaced in Nov also.

The fuel lines look ok --- a bit corroded but reasonably ok

There does not seem to be any fuel coming from the top of the spica tower (but I was allowing the car to idle while checking this in stages and not with ignition wire detached)
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post #4 of 97 (permalink) Old 03-13-2005, 06:07 PM
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Checking for fuel flow while only cranking was for safety reasons. If you've already checked with the engine running at idle, that would produce even more fuel leakage and be very apparent.

So, if I understand correctly, those cylinders are not getting any fuel leakage when you loosen the fuel pipes at the injection pump with the engine at idle speed, but you do show leakage on the other cylinders with the nut loosened? Is this correct?

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post #5 of 97 (permalink) Old 03-14-2005, 10:50 AM Thread Starter
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thats right.

No leakage on some and leakage on others.

(This all started when I was changing the spark plugs and deciced to remove the fuel lines to clean and blow them out with some carb cleaner....)
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post #6 of 97 (permalink) Old 03-14-2005, 11:07 AM
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There is no need to flush out fuel pipes with carb cleaner if it was running well. They system works at 400 psi, so blockages are almost unheard of if the system is kept clean.

When the pipes are drained, say after an install, it's necessary refill the lines by motoring the engine for about 30 seconds on the starter. That should allow a start, and maybe a little rough running for a few seconds until all air is purged.

If the engine will start, try loosening the fuel pipe at the injector and keep it loose until you see some fuel and the line is purged of air. Use hand/eye protection.

What I've said is about all I can think of. If this doesn't work, drop Wes Ingram an email. www.wesingram.com

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post #7 of 97 (permalink) Old 03-14-2005, 11:50 AM Thread Starter
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thanks...

A final question..... and other piece of info I forgot.

Is there any point in removing /cleaning the ijectors at the spica pump (not sure if these can be removed)

I forgot to mention, that the fuel pressure light on my car has never worked... on a monti it should flash a few times on startup and then go out. Mine has never flashed at startup....the dash bulb seems ok ...

Is there a way to test the sender with a test lamp or multimeter ?
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post #8 of 97 (permalink) Old 03-14-2005, 12:13 PM
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Well, I guess I assumed that since you changed the filters, that you made sure that the rest of the system was good. It sounds as if you are starting to work on your Monti without the aid of any tech manuals. I would highly discourage you from that until you have read and have a good understanding of the manuals.

Troubleshooting the Injection Pump is completely counterproductive unless the fuel supply pump is putting out sufficient fuel pressure. I believe that Montreals are similar to the others in that there is a front fuel filter with a fuel pressure switch that turns on the low pressure light at less than 7 psi.

Go to the following page on Wes Ingram's site and download the two guides on the SPICA system. One is specific to the fuel supply system and is much more comprehensive than the factory manuals and should give you all the info you need to troubleshoot and fix the fuel supply system.

http://www.wesingram.com/hp.htm

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post #9 of 97 (permalink) Old 03-14-2005, 12:33 PM Thread Starter
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thanks rtfm i guess....

I have all the manuals for the monti and have checked the fuel supply
as best I can without the working warning light. The tank was out of the car in december cleaning and the pumps were fine then.

I think the monti is suffiently different to whats described in the manuals to heap over more confusion (at least on me). For example, montis have two fuel pumps, the engine bay fuel filters is somewhat different also.

My basic assumptions was that I disturbed something while 'cleaning' the injections lines.....

I will revisit these excellent documents over the weekend and retrace my steps to see if I can fix the problem....

First step is probably to get the fuel pressure light working....

thanks for all your help
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post #10 of 97 (permalink) Old 03-14-2005, 12:59 PM
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Sounds like the Monti has a in-tank boost pump (3 psi) that feeds the main supply pump, just like the newer Spiders. The fuel pressure sending unit should be on the front fuel filter (single wire). It's a very simple on-off switch. When the switch grounds (low pressure) the light turns on.

When first turning the ignition switch to "ON", the light should come on for a second or two, until the pressure builds up, then go "OFF." It should never come on again, until the next time you go to start the engine.

To check the exact pressure in line you must use a "T" fitting. NEVER deadhead check the main supply pump. It's capable of putting out very high pressure. However, it's ok to deadhead check the low pressure (3 psi) in-tank boost pump. Nominal pressure in the fuel lines should be 10-17 psi or so with the alternator running, with the pressure relief valve opening at 17 psi.

Read the guides I wrote and let me know what you find out.

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post #11 of 97 (permalink) Old 03-14-2005, 01:10 PM Thread Starter
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thanks. I take a few photos as I go .....

In relation to the sender unit, I'd like to not spend the time tracing a wiring fault (when I really want to checl the fuel pressure) so do you think this might work...

- put a test light between power and the sender and
- the test light should go out when the pressure builds up (over 7)
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post #12 of 97 (permalink) Old 03-14-2005, 01:27 PM
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To test the continuity, simply ground the wire that connects to the fuel pressure sending unit. The low pressure light should come "ON". If it doesn't, there's a problem in the wiring or bulb.

You can try and test the pressure sending unit by connecting a test light to it, one lead to the + battery terminal, and the other to the pressure switch. If it works normally (light on with supply pump off, and off with the supply pump running), then the problem is with the car's wiring.

If the test light comes on, but will not go out, it's either a bad pressure switch or the line pressure is really low.

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post #13 of 97 (permalink) Old 03-15-2005, 01:07 PM Thread Starter
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I tried out the test of the sender by using a test lamp

Wiring diagram as follows:


Starter motor live] <-------test lamp -----> fuel pressure sender

With the ignition on, test lamp is on (lit)
Once I switch to the last point on the ingition, the fuel pump kicks in and the
test lamp goes out after about 1 second.

I think not run the engine to idle (as I did not get time today) to see if there
is any issue as the engine is run.

Given the sender looks ok, I will try to trace the wiring back to the dash to see what wrong .... but it look like I have at least 7psi...
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post #14 of 97 (permalink) Old 03-15-2005, 05:18 PM
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That's good. Looks like the fuel supply and low pressure warning sending units are ok.

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post #15 of 97 (permalink) Old 03-17-2005, 08:42 AM Thread Starter
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I have now confirmed that cylinder 3,4,5 and 7 are getting no fuel.

I think it is possible that I disturube the fuel outlets on the spica fuel while cleaning --- would this cause the fuel to get cut off or reduced ?

-Aidan
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