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Old 12-31-2009, 02:04 PM   #1 (permalink)
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Exclamation Indy 500 EFI bogging

Is there ANYBODY that understands the Indy 500 EFI ??? Seems like all of you have normally aspirated carbs which for me are pretty simple to work with. It's the fuel injection on my 1993 Indy that I believe im having problems with. With a little fuel added to the plugs it starts right up and idles great. It bogs at about 3700 rpm not allowing the clutch to even hook up. Even if I hold the throttle full open it won't clean up and rev. I've changed filters and nothing changes.
What are some of the common problems associated with this particular year and setup ?? Dirty injectors, frozen lines, plugged pickup tank tube ??
I was hoping to hear something soon today cuz it's snowing BIG TIME in Eastern WA and it's New Year's Eve family bon fire night...
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Old 12-31-2009, 07:19 PM   #2 (permalink)
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it sounds like the fuel system is not supplying enough fuel at high speed. Normally this is due to partially clogged fuel filters but you say you replaced them. I am sure you are aware there are two filters to be replaced in the fuel line , a plastic one before the fuel pump and a metal one after the fuel pump. It is important you replaced them both. There is also a screen on the end of the pickup tube inside the tank you should check for obstructions.

Now you say it will not even rev past 3700 RPM, some other things to check are that there are no codes on the computer. I assume you have tested compression and so forth to rule out a mechanical problem? It is running on both cyls?

here is some general reading for you of some threads I have posted to in the past regarding these EFI sleds
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Old 12-31-2009, 07:21 PM   #3 (permalink)
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That sounds like a bad piston to me!
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Old 12-31-2009, 11:27 PM   #4 (permalink)
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clen the injectors
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Old 01-01-2010, 10:32 AM   #5 (permalink)
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Also, an old weak battery can cause all kinds of problems too.
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Old 01-01-2010, 11:28 AM   #6 (permalink)
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EFI filters

Thanks everyone and mrholmquist. The reading of mrholmquist older posts concerning the filters has been very helpful.
Yes, I replaced the lower plastic filter(tank to pump and what a B*%* to get at !!). I did go to napa for the plastic filter and not knowing about the Nissan filter match up wasn't able to replace the metal high pressure unit. We both thought that it seemed pretty unobstructed. The plastic was pretty good also but was replaced.
Haven't checked pickup tube yet but, when I unhooked the fuel line between tank and plastic filter no fuel came out. I pressureized the tank by blowing with my mouth and then fuel came out pretty steady.
I've learned the hard way about having a weak battery so that's all good.

I'm pretty sure compression is good and that both cylinders are running. There is nothing to indicate cylinder or piston problems. I believe it's a bug that I have to find and work out.
I'm new to sleds and really appreciate everyone's input. It means alot, thank you.
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Old 01-01-2010, 09:41 PM   #7 (permalink)
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Toby, listen to Holmquist. I'm new to the efi scene with my '94 500 Indy that I got last year. When I bought my sled I was told the ECU was bad. Brought it home and tinkered around and took it out for a spin only to have it towed home after 3 miles. I was thinking I was batteling a computer issue and Holmquist was certain it was a mechanical issue. Even though my sled had a new top end, ended up being a bad piston/rings. Unfortunately I haven't been able to ride it since I rebuilt it. Hopefully sometime we'll actually get snow here in Ohio!!!!
Just a poor man trying to ride a cheap sled
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Old 01-02-2010, 10:29 AM   #8 (permalink)
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Poor man riding a cheap sled, I like that. We should start a club ha ha.
Mrholmquist is right to check compression first. But I've felt sure that it's fuel delivery. I'll check compression as soon as the recoil stater parts and repair manual arrive. I suppose at higher rpm's that it's possible Im getting blowby.
In the meantime, I pulled the gas tank and found nothing blocking the screen at the end of the pickup tube. But, what I did find was the rubber grommet that seals the fuel return line to the tank is not too good. Also, the tank vent is super small and seemed alittle restrictive.
That leads me to my next question: Is the fuel pump a push/pull type ? Im supposing the whole system is pressurized, even the tank ??

cheap guy riding a poor sled
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