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CMFI Spyder Fuel injection
12-18-2013, 11:04 AM
Post: #1
CMFI Spyder Fuel injection
1995 GMC Jimmy 4.3L 4wd

CMFI spyder fuel injectors apparently and can't see fuel from injectors.

Fuel pressure at rail port us 60 psi.
Fuel is reaching input port if spydwr.
12V LED confirms electrical pulsed at input electrical connector ( although polarity appears reversed) while cranking engine.
continuity / resistance check connector of spyder unit confirms 2.1. - 2.4 ohms.
Could only the fuel regulator cause these symptoms.
Suggestiions. ?

cferry7
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12-18-2013, 11:30 AM
Post: #2
RE: CMFI Spyder Fuel injection
So you are telling us you have this half apart and are testing it this way either on the engine or some sort of bench test?

Recalling the fuel reg is servicable on this year but if it's been sitting around it's very possible that ALL of the injectors are stuck / clogged. As long as you have a signal pulse and the voltage doesn't drop off you should be ok in that department. (ECM switches the ground) The injector squirt is VERY small and you may not be able to see it with the naked eye in most shop conditions. The assembly may also be full of air if you have been fooling with it.

I'd be curious to know what led you to get this far into things. What was the original problem? No start, runs rough, skip, etc?
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12-18-2013, 04:47 PM (This post was last modified: 12-18-2013 04:57 PM by cferry7.)
Post: #3
RE:
No Start
Using a paper towel under the injector(s) . I did see some fuel and smell it on the
Paper towel under the injector. However only one bank appeared to squirt.
Now a test again it may have been residual fuel. How can it be residual fuel when fuel us so evaporative. ??
I will test again in the vehicle as before make sure the pulses are present with unit attached and voltage does not dip. I want to try soaking the injectors and try again.
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12-18-2013, 10:54 PM
Post: #4
RE:
The fuel will not evaporate while inside the injector hoses so all you have to do is make sure there's no air pockets from having it disassembled.

It's been quite awhile since I did one of those injector change outs but recalling they all squirt at the same time and twice per cycle.... meaning it's not a sequential system in firing order. They squirt once when the valve is open and once again when the intake valve is closed. Recalling there's two (three?) solenoids in the pack so likely they are partially or totally clogged, which is a common problem. Yeah, they are expensive but replacement is the only sure cure. Wholesale prices were well over $200 last I looked and probably closer to $300 these days. (plus the gasket set)

Oh, those fuel lines get VERY brittle with age and failure is highly likely if you try to put a used set back in.
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12-20-2013, 12:16 PM (This post was last modified: 12-20-2013 12:23 PM by cferry7.)
Post: #5
RE: CMFI Spyder Fuel injection
Thanks !! I Purchased a used unit from salvage yard.Cleaned it .installed it and it worked.Removed it tcleaningit more thoroughly ..Replace two injectors. Wow spraying the actual injectors appears old fuel dir nold fuel just Jeeps coming out. Takes a lot of cleaning.Thankful I was able to find thus used bit for test purposes.
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12-20-2013, 12:21 PM
Post: #6
RE: CMFI Spyder Fuel injection
Sounds like you are on the right track!
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