starting & running

HI-OUTPUT

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So yesterday morning (friday) with the engine warmed up and ready to go I was driving the SC all day (10am-8pm) shifting gears at high RPM's (over 3) like if it was a 5.O mustang. I stopped and turned off the car at many places around town for some appointments, after with no problems starting the car back up to visit and leave somewere else.

Today (saturday) in the morning (8am) I was having a hard time starting up the car, the starter was turning but the car didnt want to start up so I kept pumping the accel pedal but still no luck. I disconnected the two harnesses that plug into the DIS module checked the inside o.k. then plugged back on.
Pumping the accel pedal I cranked up the ignition one more time, Barely the engine started up finally so I warmed it up and drove off, while driving off about 2miles at high RPM (over 3 continuously) , the RPM gauge started going down and up crazy and my car started backfiring, pinging & stalling "check gauges" and "yellow arrow" signals turn on then the car turns off..

Ive noticed when I take it easy on the RPM (less then 3) regular shift driving the car is ok, but when Im on High RPM (over 3 continuously) the engine starts stalling & the exhaust backfires..

For now the SC does start up! I have to drive the car carefully, but what I dont want is the rpm gauge to act crazy, Engine stall, Engine turn off, While driving the car in the streets.

Would anybody have a similar problem with the engine cranking but not starting up but then after a while it starts up after you checked something? & what must be done to fix the high continuous rpm street driving on 1st 2nd 3rd 4th 5th, Im not exactly shure on what gear I was on I think it was 3rd, I can test again anytime just to make shure..
 
sounds like a cam sensor to me. had the same symptoms plus lopey idle, changed the cam sensor and all is well.
 
Agreed. Also, pumping the accelerator when trying to start the engine isn't helping anything. It isn't carbuerated. ;)

-Rod
 
thanks for the cam sensor I will still keep in mind

When everything that was happening my Fuel Tank was less then Half, but it wasnt Low on fuel.

I already filled up the Tank to full and the problem has stopped. Ive been using Shell 87 regular unleaded for about 3 months & for the last couple of months Ive been mixing the fuel with a highoctane fuel concentrate 1 bottle about every 4 weeks.

I remember before when I was using premium 91 and no concentrate the fuel would be very low and everything would still be o.k. & the car still ran smooth. Should I change back to premium 91, or would regular 87 still be o.k. to use?
 
its a supercoupe

do not put in anything less than premium, whatever that may be in your area.

dont know if your experiencing detonation, but you should stop with the 87 gas and go premium...
 
even with adding that "high octane" additive crap the regular fuel's octane rating was MAYBE 88. most additives, if they're lucky only bump it up about 1point.

if u want some REAL high octane stuff go get a drum of 110 racing fuel !!:D
 
there is a reason there are "premium fuel " stickers all over the place---you are going to damage your engine if you continue with the 87 octane if you haven't already..............Dan
 
even if u can put an entire 19 gallons in the tank for a fill up, thats only $3.80 difference from regular to premium.

is that really worth possible damage to your engine ? not to me it isnt ;)
 
cranking but no start up

thanks everyone I'll make shure to always use premium 91 or higher

Im also thinking since Ive been using 87 fuel would you think thats whats giving my starting problems and backfiring?

(Sunday)Cam sensor was replaced with new one, started fine and less Backfire then before for two days, But Now today (Wendsday) the car cranks quick but doesnt start up. When installing the Cam sensor is there any specific instructions on how to install or do you just mount bolt on and go? What can be the possibilities of my car not wanting to start up?

do not put in anything less than premium, whatever that may be in your area.

dont know if your experiencing detonation, but you should stop with the 87 gas and go premium...

What is "experiencing detonation"

ehrm, nevermind.....

yeah premium.....OR pull octane plug at the VERY LEAST

"pull the octane plug" what does that mean?
 
the 87 octane fuel was possibly giving u detonation. which is when the fuel combusts b4 the spark plug has a chance to ignite it. premium gas, with its higher octane combusts at a higher temperature. so its less likely to pre-ingnite.

i think the hard-starting and backfiring was from the cam sensor. it happened on my SC when the sensor started going out. replaced it and good as new.

when i installed my new cam sensor, i disco'd the battery and the sensor, unbolted it, pullled the old off and put the new on. bolted back in, connected everything and fired her up.

check wut ur fuel pressure is at the rail with a fuel pressure gauge. hook it onto the lil valve next to the coil pack. should be 40, i think, at idle.
 
My experience recently

'Would anybody have a similar problem with the engine cranking but not starting up but then after a while it starts up after you checked something?'

I had same thing for two months on a recently purchased 1990 SC w/90k miles. Sometimes hard starts, w/tach signal loss & stumble, then ok...then not.

I swapped in a spare DIS module and none of those issues have happened since.

The DIS that came off was a no-name brand and the one that went on is Motorcraft.

The reason why it finally starts is supposedly due to the computer supplying defaults from stored tables if various signals are missing and/or out of spec.

Don't be too confused by all the electronics when troubleshooting a problem. Remember an additional item...each time you turn the key on/off to try to start, you are cycling the one mechanical item in the system - the ignition switch.

More than one owner has had a 'no-start' or 'sometimes-start' condition where the switch came out in pieces when they went to check/replace it. These cars are pushing twenty years in some cases, and that's a lot of action on the switch. Easy to look at and low cost to replace.
 
With the "yellow" upshift light coming on that normally indicates a crank position sensor. I would try the cam sensor first and if that does not fix it then the crank sensor.

Ed

’94 SC Red Auto: 110,000 Miles, Headers, No Cats, Pro Torque 2500 Stall Converter, TRANSGO Shift Kit, 10,000 Lbs Auxiliary Tranny Cooler, Tranny Fluid Temp Gauge, 3.73 Gears, 70mm BK Throttle Body, 76mm C&L MAF with Gold Tube, A/F Ratio Gauge, Raised SC Top, Teflon IC Seals, ’90 XR7 SC Pulley, ARP Head-Rod-Main Studs, Scorpion 1.73 Rockers, Solid Motor Mounts, Iridium Plugs, Live Wire Plug Wires, Screamin’ Demon Coil, 36# Accel FIs, Custom Air intake, K&N 9” Cone, Royal Purple Synthetic Lubricants and Optima Yellow Top.
 
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