Injectors not opening

[smpiers]

I have just reinstalled my engine after replacing all vacuum lines, fuel lines. Had the FI harness rebuilt and replaced all fuel injectors with rebuilt ones. The problem I am having is that the fuel injectors are not squirting any fuel. When I pulled one bank of injectors (#1 and #2) and placed in vials there was no fuel present after turning over engine. When I pushed in the pin on the injector though, gas shot out. I have tested all fuel injected components for the proper resistance via the pins on the harness brain connection. Any ideas here?
FI is a '76 2.0 D jetronic.

Thanks,
Shane

[Dave at Pelican Parts]

Check the ground connections. I believe that the two injectors on each side share one ground connection.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[HMeeder]

Also:

Check the connections and contacts for the injector points on the distributor.

Good luck!

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Herb
'72 1.7 Tangerine 'Teen
'74 2.0 Red Rustmobile

[Jim Smolka]

Also, using an Analog volt meter, measure the voltage going to the injectors. You should see it pulse on and off.

I agree, it could be the switches inside of the dizzy. It could also be the brain, but not likely.

Good luck

[smpiers]

I went home for lunch and checked out the suggestions. No luck. HOWEVER, I did notice the resistance on my MPS went from the correct 350 ohms to and open circuit. A little nudge and the resistance would come back. Reading an article I downloaded from the PP tech. site states that a faulty MPS will result in injectors not opening. Now, can I rebuild a MPS? Do more testing on it to be sure this is the culprit?

Thanks for the replys so far.

Shane

[pbanders]

I'll have to check again to be 100% certain, but I believe the grouped injection pairs are 1/4, and 2/3, so if you're having problems with 1/2, I don't think it's likely that the trigger contact points are to blame.

To check the grounds as DD suggests, unplug the ECU and probe both of the injector plug contacts - one should be ground, the other open.

Another possible way to check the injector voltage pulses is to use a "Noid" light, available from places like AutoZone for about $7. I bought one the other day just to try it out, but I don't know for a fact that it works. I'll try it tonight if I get a chance and will post on the results.

If your MPS is bad none of your injectors will open. Where are you "nudging" the MPS?

Here's what I'd do to diagnose the MPS:

1. Use a hand vacuum pump with a gauge (Actron model from FLAPS, about $30, handy for many other uses) and pull 20 in. Hg of vacuum on the port. It should hold within 1-2 in. Hg after 1 minute. If it drops rapidly, it is likely the full-load diaphragm is cracked due to metal fatigue. Get a rebuilt unit.

2. Measure the primary and secondary resistances. Primary = 90 ohms, Secondary = 350 ohms. Measure resistance from all contacts to the case - all should be open.

There are some other tests I can describe if you have access to an inductance meter (e.g. Wavetek 27XT DMM).

Home rebuilding of these units is generally not recommended. There are no commercially-available replacement parts, and disassembly will likely result in a non-functional MPS that cannot be used as a core for a rebuilt unit.

Brad Anders

[smpiers]

I went thru the whole system again last night. I found that the injectors were giving me a resistence reading of 3.7 - 4.2 ohms. Should be reading 2.4 ohms. So, I took of the grounds, resanded the ground plate and where it contacts the engine. Placed put back together and have the same readings. I AM using rebuilt fuel injectors. The injectors have the 73-74 2.0 part number, my car is a 76 2.0. Is this bad? Other than that, everything checks out okay now. I snugged up the MPS wire fitting and that seems to have cleared up that issue. I am going to take some electrical cleaner and go thru all the connections. thanks to all who have helped so far, I will take more advice if you have it. I REALLY want to drive my car by this weekend.