Hello All,

I have a question about replacement of the fuel injection spider. I replaced it on my 99 blazer this past weekend and I put in the standard motor products fj503. I started the Blazer and it ran horribly and skipped real bad. After doing further research, I realize that I left the plastic covers on the end of the fuel injectors. Now i'm seeing on the Standard motors products website that I should have removed them. Should these be removed?

The Blazer didn't run longer than 5 minutes and didn't have chance to get to operating temperature. I'm concerned that the plastic coverings might have melted in the lower intake, which will lead to me having to replace the lower intake manifold if further damage hasn't been done. Please let me know. Thanks for any help!

Dale

 

IF they came off the injector heads they probably made it into the engine. I would think that they would get blown out the exhaust and would wind up as a goober in the catalytic converter. Eventually it would probably burn off. One way or another they will have to come out, so I suggest you pull the spider and see if they are still there or not. If some are missing then dont worry about it unless it still runs poorly after you put it back together. Im betting that all the caps will still be on the injectors.

Good Luck.
-William

 

If the plastic caps you are referring to are the yellowish/white caps, then I believe those are supposed to be there...

Another thing you can check is that you did not bend over any pins when installing the main fuel injector harness connector into the spider.

 

Yeah the yellowish/white plastic tips that are on the end of each injector are the ones I am talking about. I see them in all the pictures online except for the Standard Engine Performance website.

http://www.standardbrand.com/Online%...g/Content.aspx

On Amazon's website they show them with the tips on...

http://www.amazon.com/Standard-Motor...4695575&sr=8-1

If the tips do stay on, what do you all think it could be? It ran decent before except for a cylinder 4 misfire. After I put everything back together the engine's idle would be erratic and rough. If I put the truck in drive it would jump between 3,000-3,500 rpm and start to drive without touching the gas pedal. I could also tell by the exhaust that the motor was skipping as if it were misfiring.

New plugs, new fuel pump, new wires, new coil, new distributor cap, new rotor button. I've replaced just about everything in the past year.

Are the fuel injectors on the spider cylinder specific? I'm pretty sure I positioned them correctly.

Thanks for the responses. I appreciate the help!

Dale

 

The injectors MUST be put into the proper cylinders for things to work correctly.

 

Its probably the wires that go to the spider , they are known to go bad .

 

I left the install sheet at the garage I was working on the Blazer at. I'm trying to remember, but I think the fuel injector lines were lined up in the right position out the box other than moving to make some adjustments. I can't remember the cylinder order that was printed on each side of the unit.

The only two things I could think it would be at this point is I mismatched some of the injectors to the cylinders, or either the unit is defective.

Unfortunately I won't get to tear it down again until Sunday. I don't want to, but I'm debating on having it towed to the GM service center.

 

After brainstorming and troubleshooting I'm beginning to think the upper intake mainfold is not sealing good. I did not replace the seal this time because I replaced it back in September when I put new upper and lower intake manifold gaskets on. The old seal/gasket did have a wet gas residue from the old spider being bad.

Can an air leak cause a bad sputter/misfire? Also i've read online that it can cause the car to accelerate on it's on, which is what it did.

Or either the Idle Air Control Valve has gone bad as well.

 

If checking to make sure that there isn't a pin or two bent under the main spider electrical connection shows that everything is perfectly fine, I would suspect a problem with the routing.

You can diagnose a vacuum leak with an unlit propane torch by tracing around the sealing surfaces.

Known to go bad on the CPI engines. Not so much on the SCFI engines. And since the spider is a new MFI upgrade, the wiring from the spider body to the injectors at the end of the tubes is new as well.

 

This is the freeze frame data I collected before I changed the fuel pump and spider.

Calc Load 14.51
ECT (C) 72
STFT B1 2.34
LTFT B1 0.00
STFT B2 2.34
LTFT B2 -0.78
MAP (kpa) 56.00
RPM 1617
Speed 73
MAF(g/s) 25.36
TPS 11.37

I was thinking that the MAP reading was on the high side. Also the LTFT B2 being negative, not sure if that is good or not.