95 5.0 Running Rough and Occasionally Won't Start!!!!!
03-03-2015, 09:38 PM
#1
Member
Thread Starter
95 5.0 Running Rough and Occasionally Won't Start!!!!!
Hey guys and gals,
I need a little help. Have a 95 5.0. 4x4 automatic. I recently purchased the truck from a buddy. It had been sitting for a few months. I'll start off by saying I love the truck and for the most part it's been ok to drive but lately it's driving me crazy. First off it runs rough at idle or low RPM's. When I have my foot in it there is no problem but at a light it runs rough and strangely when I slow down around tight corners then get back on the accelerator it stumbles/hesitates until the RPM's are back up. And now it will throw fits starting about once every 2 weeks or so. I'll turn the key and it will turn over but it runs ROUGH (feels like only 4 cyl are firing) then stumbles and dies. At that point it can take up to 15 min of trying to finally start and when it does it starts ROUGH then smooths out. While it's stumbling if I press the gas at all it dies immediately. I just have to wait for it to smooth out itself. Has new plugs, wires, cap, rotor, fuel filter, and my buddy said he replaced the distributor recently. I can hear the fuel pump prime when I turn the key on. I will occasionally get the check engine light while I'm driving but it only stays on for maybe 10-30 seconds then turns off. Any ideas would help me a lot!!!!!!!!!!! Thanks in advance!
I need a little help. Have a 95 5.0. 4x4 automatic. I recently purchased the truck from a buddy. It had been sitting for a few months. I'll start off by saying I love the truck and for the most part it's been ok to drive but lately it's driving me crazy. First off it runs rough at idle or low RPM's. When I have my foot in it there is no problem but at a light it runs rough and strangely when I slow down around tight corners then get back on the accelerator it stumbles/hesitates until the RPM's are back up. And now it will throw fits starting about once every 2 weeks or so. I'll turn the key and it will turn over but it runs ROUGH (feels like only 4 cyl are firing) then stumbles and dies. At that point it can take up to 15 min of trying to finally start and when it does it starts ROUGH then smooths out. While it's stumbling if I press the gas at all it dies immediately. I just have to wait for it to smooth out itself. Has new plugs, wires, cap, rotor, fuel filter, and my buddy said he replaced the distributor recently. I can hear the fuel pump prime when I turn the key on. I will occasionally get the check engine light while I'm driving but it only stays on for maybe 10-30 seconds then turns off. Any ideas would help me a lot!!!!!!!!!!! Thanks in advance!
Last edited by AmericanInfidel55; 03-03-2015 at 09:40 PM.
03-04-2015, 11:47 AM
#4
I having the exact same problem ! I've replaced a whole lot including plugs plug wires distributer cap and rotor and ignition coil . It'll run good for a couple minutes then start crapping out. There's only a few more things I believe i can replace to fix it but other than that i dont know what's wrong .
03-04-2015, 12:30 PM
#5
1994 F150 XLT 5.8L 2wd
Have you pulled your codes? Tested voltage on the TPS? Verified fuel pressure? Before throwing parts at something at least narrow down your options, regular "tune up" components are always a good idea if it's been a while since they were changed but before dropping money on parts run some basic tests.
Proper fuel pressure varies between years (40ish for 92+, 50+ for pre 91- I think or something like that), should hold pressure for a few minutes after shut down.
Engine vacuum should be 17-22hg and steady, when throttle is bumped it should drop then rebound and hold steady
Compression should be less than 15% difference between highest and lowest.
Ensure no vacuum leaks from small diameter lines coming from the manifold tree.
TPS .9-.97v closed throttle, 5v WOT with a smooth increase.
Always a good idea to clean up grounds with emery cloth/wire brush, connectors with quick drying electronic clean, thin coating on both with dielectric grease.
Cleaning the TB blades and IAC is always helpful, doing the entire TB is pointless in my opinion because after about 50 miles it's covered in residue again, but it is essential that the blade edges are clean as well as where they come into contact/close proximity to the TB.
EDIT: If it runs fine for a few minutes then pooches, it's probably happening when the truck goes into closed loop. It runs open loop for a couple of minutes to let the sensors and what not warm up to operating temp, then starts basing it's decisions off of the info that it is receiving. This would suggest that something sending a signal to your ICM or ECM is defective. Should show up in the codes as it'll be a communication issue and will be flagged by the computer, though this won't necessarily turn your CEL on it will definitely produce a code.
Proper fuel pressure varies between years (40ish for 92+, 50+ for pre 91- I think or something like that), should hold pressure for a few minutes after shut down.
Engine vacuum should be 17-22hg and steady, when throttle is bumped it should drop then rebound and hold steady
Compression should be less than 15% difference between highest and lowest.
Ensure no vacuum leaks from small diameter lines coming from the manifold tree.
TPS .9-.97v closed throttle, 5v WOT with a smooth increase.
Always a good idea to clean up grounds with emery cloth/wire brush, connectors with quick drying electronic clean, thin coating on both with dielectric grease.
Cleaning the TB blades and IAC is always helpful, doing the entire TB is pointless in my opinion because after about 50 miles it's covered in residue again, but it is essential that the blade edges are clean as well as where they come into contact/close proximity to the TB.
EDIT: If it runs fine for a few minutes then pooches, it's probably happening when the truck goes into closed loop. It runs open loop for a couple of minutes to let the sensors and what not warm up to operating temp, then starts basing it's decisions off of the info that it is receiving. This would suggest that something sending a signal to your ICM or ECM is defective. Should show up in the codes as it'll be a communication issue and will be flagged by the computer, though this won't necessarily turn your CEL on it will definitely produce a code.
Last edited by fltdriver; 03-04-2015 at 12:35 PM.
03-04-2015, 10:30 PM
#6
Have you pulled your codes? Tested voltage on the TPS? Verified fuel pressure? Before throwing parts at something at least narrow down your options, regular "tune up" components are always a good idea if it's been a while since they were changed but before dropping money on parts run some basic tests.
Proper fuel pressure varies between years (40ish for 92+, 50+ for pre 91- I think or something like that), should hold pressure for a few minutes after shut down.
Engine vacuum should be 17-22hg and steady, when throttle is bumped it should drop then rebound and hold steady
Compression should be less than 15% difference between highest and lowest.
Ensure no vacuum leaks from small diameter lines coming from the manifold tree.
TPS .9-.97v closed throttle, 5v WOT with a smooth increase.
Always a good idea to clean up grounds with emery cloth/wire brush, connectors with quick drying electronic clean, thin coating on both with dielectric grease.
Cleaning the TB blades and IAC is always helpful, doing the entire TB is pointless in my opinion because after about 50 miles it's covered in residue again, but it is essential that the blade edges are clean as well as where they come into contact/close proximity to the TB.
EDIT: If it runs fine for a few minutes then pooches, it's probably happening when the truck goes into closed loop. It runs open loop for a couple of minutes to let the sensors and what not warm up to operating temp, then starts basing it's decisions off of the info that it is receiving. This would suggest that something sending a signal to your ICM or ECM is defective. Should show up in the codes as it'll be a communication issue and will be flagged by the computer, though this won't necessarily turn your CEL on it will definitely produce a code.
Proper fuel pressure varies between years (40ish for 92+, 50+ for pre 91- I think or something like that), should hold pressure for a few minutes after shut down.
Engine vacuum should be 17-22hg and steady, when throttle is bumped it should drop then rebound and hold steady
Compression should be less than 15% difference between highest and lowest.
Ensure no vacuum leaks from small diameter lines coming from the manifold tree.
TPS .9-.97v closed throttle, 5v WOT with a smooth increase.
Always a good idea to clean up grounds with emery cloth/wire brush, connectors with quick drying electronic clean, thin coating on both with dielectric grease.
Cleaning the TB blades and IAC is always helpful, doing the entire TB is pointless in my opinion because after about 50 miles it's covered in residue again, but it is essential that the blade edges are clean as well as where they come into contact/close proximity to the TB.
EDIT: If it runs fine for a few minutes then pooches, it's probably happening when the truck goes into closed loop. It runs open loop for a couple of minutes to let the sensors and what not warm up to operating temp, then starts basing it's decisions off of the info that it is receiving. This would suggest that something sending a signal to your ICM or ECM is defective. Should show up in the codes as it'll be a communication issue and will be flagged by the computer, though this won't necessarily turn your CEL on it will definitely produce a code.
Fuel pressure has to be 30 to 45 psi - close to 30 is very bad.Under 30 it won't run. KOEO you'd be looking for 42 ish. That should drop 5 psi or so when you start it and it's idling, because higher vacuum opens the fuel pressure regulator. As you open the throttle and vacuum drops, the regulator will close and you should see the pressure climb back up.
Just for reference, all the SB V8's run at 30 to 45, pre 95 4.9's are 45 to 60 which changed (mid 94 ?) to 30 to 45 psi.
That bit about the 4.9's doesn't apply to yours, I just threw it in there.
I posted something not too long ago "testing the TPS". That's done with any cheapy multimeter. The TPS can cause all kinds of problems if it's not functioning right.
And being your truck is OBD1 you can check for codes without a code reader. Check the sticky post at the top of the page by 'just call me sean'
03-30-2015, 08:43 AM
#7
Member
Thread Starter
Wow. Thanks guys for the info. Sorry for the delay. Life has been crazy. Still having issues but will pull codes this week and report back. This morning it started great and ran but as soon as I turn the headlights on it dies completely. It just cranks and cranks until I turn the headlights back off then it starts like a champ. Any ideas? 5 month old battery and week old starter.
Trending Topics
03-30-2015, 09:09 AM
#8
Anything is just a wild guess until you pull codes and check a couple things mentioned in earlier replies.
The current issue does sound electrical. Is it just the headlights or does it die with just the marker lights on as well ? When it is running with the lights off do your daytime running lights (headlights) come on ? They should.
Daytime running light module is on the front of the rad saddle bottom left, more or less behind the bumper/turn signal. That or the headlight switch or maybe there's a short or power draw or maybe the alternator isn't working as good as you think it is.
Multimeter - volts dc - positive to negative 12.6 volts resting, 14.5 volts running
The current issue does sound electrical. Is it just the headlights or does it die with just the marker lights on as well ? When it is running with the lights off do your daytime running lights (headlights) come on ? They should.
Daytime running light module is on the front of the rad saddle bottom left, more or less behind the bumper/turn signal. That or the headlight switch or maybe there's a short or power draw or maybe the alternator isn't working as good as you think it is.
Multimeter - volts dc - positive to negative 12.6 volts resting, 14.5 volts running
03-30-2015, 12:11 PM
#9
Member
Thread Starter
Anything is just a wild guess until you pull codes and check a couple things mentioned in earlier replies.
The current issue does sound electrical. Is it just the headlights or does it die with just the marker lights on as well ? When it is running with the lights off do your daytime running lights (headlights) come on ? They should.
Daytime running light module is on the front of the rad saddle bottom left, more or less behind the bumper/turn signal. That or the headlight switch or maybe there's a short or power draw or maybe the alternator isn't working as good as you think it is.
Multimeter - volts dc - positive to negative 12.6 volts resting, 14.5 volts running
The current issue does sound electrical. Is it just the headlights or does it die with just the marker lights on as well ? When it is running with the lights off do your daytime running lights (headlights) come on ? They should.
Daytime running light module is on the front of the rad saddle bottom left, more or less behind the bumper/turn signal. That or the headlight switch or maybe there's a short or power draw or maybe the alternator isn't working as good as you think it is.
Multimeter - volts dc - positive to negative 12.6 volts resting, 14.5 volts running
04-03-2015, 08:14 AM
#10
Check for codes, AND check FUEL PRESSURE with a guage ! Without these 2 important first steps,your wasting your time and money going any further..... Hearing a pump run OR gas squirting out the shrader valve is NOT a pressure test
Last edited by FORD TUFF; 04-04-2015 at 01:39 PM.