Stumble under heat

I've been watching this club for at least a couple of years - y'all are a great group, good resource. I'm hoping you may help me with an engine electical problem. My 93 LSC will appear to loose engine power under conditions of Hot summer days when in stop and go - will stumble for maybe 1/2 a second and pick up again. No codes (using the blinking malfunciton light with DLT bypass in either keyoff/keyon. I believe it's the VCRM with a thick-film seperation problem or the engine control (EEC-IV) on the wheel tower next to brake master cyl. It appears to be loss of ground somewhere but I've checked all my grounds - just couldn't find the one behine the radio (looked like a metal strap, no wire). This also only seems to happen when A/C is on. I'd replaced the DPFE and both HO2S in past 2 years and had the fuel rails and throttle cleaned up. All stock no mods.

Your wisdom would be nice - best wishes

Christopher Bennett
93 Black LSC
Bristow, VA

RE: Stumble under heat


I can't tell you for sure what it is but the 90 Cougar I used to have started doing that AND stumbling for a few seconds on startup if it was only off a few minutes on a real hot day. About a month later the fuel pump quit. After fixing the pump the problem was gone. I think it wasn't holding enough pressure to keep the fuel from vaporizing under the hood on a hot day. My Mark has done it a couple times lately. If it gets worse In the hot weather, I'm putting in a new pump. It has 182,000 on it so It could probably use help by now anyway.

ayne

RE: Stumble under heat


I did a bad Thing. Read the text then typed my name, Without Looking.

Wayne

RE: Stumble under heat

Thanks for the info, thinking that the VCRM contains the High-Speed Fuel pump relay that has relevance. Makes me think maybe I'm due for a fuel filter change also so maybe I'll try the filter and chase the power feeds to the pump for damage.

Christopher Bennett
Bristow, VA
93 Black LSC