my car starts up fine and idles kinda rough ,after about 20 min of letting it run the CEL comes on for code 43 and once that comes on the the idle with drop to like 300 and raise up to 800 and constantly do it ,, we have checked everything , all wiring is right , by the way it sa 91 hatch dx converted to obd1 with 92 ls motor ,, so if anyone has any suggestions please let me know ,,,

 

Can you get a little more specific with what you have tried? ..i dont wanna give suggestions if you have already done them

 

we have messed with tps , IACV , main relay , injectors are good , wiring good , map sensor ,, cant think of anything else it could be

 

oh yea tryed to different plugs , diff ls dizzy and a diff ls ecu and still does it ,, we narrowed everything down to fuel pump or FPR ,,

 

I had the same problem with a 91 ls. I just got so pissed off I just taped the light and it went away. it could be the o2 sensor or the little selinoid on the firewall that the fpr connects to

 

This is the problem im bbrians freind. The car runs like crap idles low and stumbles at part throttle. It feels like its not gettin enough gas. Its a dx ef hatch converted to obd1. It throws a cel 43 which is fuel supply system after about 5mins of running. So far it has known good injectors, new fuel filter, tried a diffrent tps sensor, diffrent ecu, diffrent known good dizzy, has all new ground wires, tried another main relay. Still this damn problem were gonna test the fuel pressure as soon as we get a gauge. I have my money on a pump ,but any other imput would be great

 

I've heard of people having to replace their fuel pump when they swap because a 15 year old pump isn't gonna put out as much as a new one, and I've heard of h22s swaps or b series turbo cars needing high flow pumps due to leaning out and fuel starvation at high rpm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by el_payaso &raquo;</TD></TR><TR><TD CLASS="quote">I've heard of people having to replace their fuel pump when they swap because a 15 year old pump isn't gonna put out as much as a new one, and I've heard of h22s swaps or b series turbo cars needing high flow pumps due to leaning out and fuel starvation at high rpm </TD></TR></TABLE>

yea, thats what im guessin we've checked everything else and the plugs defintley show its running lean. Now only if that damn gauge would get here so i could make sure

 

Try goin to your local parts store, they should have a performance section and they have a fuel pressure guage that they sell in like the v8 section you can buy fittings to make it work but its only the type of guage that stays in the engine bay, its like the size of a nickel, watch to see if the pressure drops off when it starts bogging. If you need a new pump, JEGS sells a pump that's similar to a walbro for only like $109 plus shipping but it ends up bein cheaper than a stock one

 

My fuel pump is brand new and I still have the same lean problem you are talking about. The spark plugs are iridiums, but very white on the ends signifying a lean fuel mixture. I have yet to figure out why the expletive this is happening, but it is not the fuel pump. I suspect vacuum leak, or something else. I never get a CEL but the car runs very poorly.

 

vacuam leaks cause a high idle thought not low? Im thinking if its not the pump or regulator maybe a valve is bent slightly. What is your car and setup and what conversion harness are you running?