Only starts after block heater is plugged in

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Darkimag22

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After a week of being -30 to -40C, and then Christmas, I am finally going to be replacing the spider injection with a new and upgraded MFI spider. After talking to a couple mechanics about the symptoms I'm having, they keep going back to a possible clogged/gummed up injector(s). It now takes 4 or 5 seconds of cranking before it will slowly fire after being warmed up. This is the exact same thing that was happening when the stock original spider injector was leaking/failing. Wish me luck lol.
 
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Darkimag22

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Finally got the upgraded spider installed. The intake was wet on the back half so something was definitely leaking. Buttoned everything up and now I'm getting a P0300 code (random misfire) and runs super rough. Pulled the spark plugs (didn't look too bad but smelled like diesel still) and will be replacing them this evening. If that doesn't fix it, I guess I'll tear it all apart again.
 

Schurkey

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now I'm getting a P0300 code (random misfire) and runs super rough.
Is your scan tool capable of displaying individual-cylinder misfire codes?

Cheap scan tools LIE about some codes. They'll display P0300 when the REAL code might be cylinder specific--P0304, for example.

Check the cylinder-by-cylinder misfire COUNTS instead of just the misfire code(s). Maybe you can narrow down the problem to a specific cylinder or two, which makes diagnosis lots easier.

You did get the injectors/harnesses plugged into the correct intake runners...right? Plug wires connected to the proper spark plugs?
 

Darkimag22

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New spark plugs, same result. Misfires, running rough, strong smell of gasoline. Pulled it all apart again last night just to make sure everything was where it should be. Pulled the brand new spider and everything looks to be ok. One thing, however, is that there was no fuel pressure to bleed off when I removed the feed and return lines. I really wonder if i have a bad spider in all honesty.

I keep forgetting I have a HP Tuners programmer that I am sure I can troubleshoot with. Can anyone point me in the right direction...what should I be looking for when logging???
 

RichLo

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How fast does the fuel pressure bleed of with key-on/engine-off condition?
 

Darkimag22

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I didn't check before I tore everything apart. I will tonight once everything is buttoned up again.
 

Darkimag22

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I read somewhere on this forum that you will see lower fuel pressure after installing the MPFI spider. I got a reading of 55 psi that slowly dropped to 50 psi after a couple minutes. Does this sound about right???
 

Vikingdude

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My understanding is that with the MFPI injector, you need a consistent 62psi of fuel pressure pre-start. Running you should have pressure in the mid 50s. Upgrading often reveals weak fuel pumps, or clogged filters.
 
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