1989 F150 4.9 Loping idle fixed with exhaust
09-27-2011, 04:15 PM
#1
1989 F150 4.9/300 5 speed
Thread Starter
Join Date: Jul 2011
Location: Raleigh, NC, USA
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
1989 F150 4.9 Loping idle fixed with exhaust
Bought the truck. Drove it home. Drove it around for a few weeks with no problems. All on the front / midship tank. Decided to try the rear tank. Added 5 gal and drove for about 4 of those. There was a VERY strong gas smell. Noticed the gas was trickling from rust pinholes under the gas tank onto my hot exhaust pipe. Parked it for a day on an incline so all the gas came out of the holes into a BoJangles cup 
. Switched back to the front tank and drove for a few miles. Seemed fine so I filled up the front tank. Drove for another day and then when I started it up one night it drove 20 feet and stalled out. After letting it sit for a while it will start for about a second before stalling again. That was over a month ago and I've been searching this forum and trying to fix it since then. Learned a lot, but can't seem to find everything with the search button, so if I overlooked something obvious, just point me in the right direction.
Using the Clymer manual (horrible, the Haynes for my Civic is better), this is short version of what I have found. Changed the fuel filter and found orange rust silt all in it, so I realized the rear tank was full of more than just holes and sucked all it's rust into the fuel system. Front tank looks like it's newer than the rest of the truck. New fuel filter didn't solve it. When I put the key in the on position the high pressure pump can be heard operating the entire time. Is this normal? I thought it was supposed to come on momentarily. I replaced the high pressure fuel pump, thinking it was making the noise because it was faulty. The new one did the same thing. Clymer manual states psi should be 50-60psi ; I'm at 55psi quick and steady. Clymer manual also states that when you turn the truck off, you should lose no more than 5psi ; I lose 4psi, so it's textbook there too. Took the plugs out and WOW, how did this thing ever run on some of those? Sure that I had found the fix, I replaced the plugs and it will start for about 2 seconds after sitting for a while and then stalls. Seeing all the gunk on some of the plugs made me think some of the injector filters must be clogged with that stuff. Took out the injectors and they and their filters look fine. I made one of those injector testers and the solenoids in them click when I give them juice. Will use it to clean them when the service kit (with filters) arrives from RJM Injection Tech.
http://rjminjectiontech.com/products/inj-kit
Looking at the injectors, only some of the pintle caps were dirty on them, and nothing looked clogged, so I don't think that will be the problem either. After all the work of getting them out, though, I'm staring at the fuel pressure regulator, not really knowing what it does, if it could be the problem and not really wanting to take it all apart again later just to replace that bugger. Can't keep throwing $ at parts without diagnosing them properly first, so how often do those things go bad? I may just drop $32 on it and replace the PCV valve too since I removed all the stuff it was hiding behind. Anyone have ideas on the plugs? They look worse than any pics I've seen in manuals. Even the threads were filled with black grime like someone took the plugs out, dumped dirt in the engine and then put the plugs back in. I'll try to post some pics.
http://photobucket.com/SeanAA
. Switched back to the front tank and drove for a few miles. Seemed fine so I filled up the front tank. Drove for another day and then when I started it up one night it drove 20 feet and stalled out. After letting it sit for a while it will start for about a second before stalling again. That was over a month ago and I've been searching this forum and trying to fix it since then. Learned a lot, but can't seem to find everything with the search button, so if I overlooked something obvious, just point me in the right direction.Using the Clymer manual (horrible, the Haynes for my Civic is better), this is short version of what I have found. Changed the fuel filter and found orange rust silt all in it, so I realized the rear tank was full of more than just holes and sucked all it's rust into the fuel system. Front tank looks like it's newer than the rest of the truck. New fuel filter didn't solve it. When I put the key in the on position the high pressure pump can be heard operating the entire time. Is this normal? I thought it was supposed to come on momentarily. I replaced the high pressure fuel pump, thinking it was making the noise because it was faulty. The new one did the same thing. Clymer manual states psi should be 50-60psi ; I'm at 55psi quick and steady. Clymer manual also states that when you turn the truck off, you should lose no more than 5psi ; I lose 4psi, so it's textbook there too. Took the plugs out and WOW, how did this thing ever run on some of those? Sure that I had found the fix, I replaced the plugs and it will start for about 2 seconds after sitting for a while and then stalls. Seeing all the gunk on some of the plugs made me think some of the injector filters must be clogged with that stuff. Took out the injectors and they and their filters look fine. I made one of those injector testers and the solenoids in them click when I give them juice. Will use it to clean them when the service kit (with filters) arrives from RJM Injection Tech.
http://rjminjectiontech.com/products/inj-kit
Looking at the injectors, only some of the pintle caps were dirty on them, and nothing looked clogged, so I don't think that will be the problem either. After all the work of getting them out, though, I'm staring at the fuel pressure regulator, not really knowing what it does, if it could be the problem and not really wanting to take it all apart again later just to replace that bugger. Can't keep throwing $ at parts without diagnosing them properly first, so how often do those things go bad? I may just drop $32 on it and replace the PCV valve too since I removed all the stuff it was hiding behind. Anyone have ideas on the plugs? They look worse than any pics I've seen in manuals. Even the threads were filled with black grime like someone took the plugs out, dumped dirt in the engine and then put the plugs back in. I'll try to post some pics.
http://photobucket.com/SeanAA
09-27-2011, 05:09 PM
#2
Senior Member
Wow... those plugs look... TERRIBLE!!!
Glad you replaced them! Ive taken the fuel rail to the injectors off, leaveing the injectors attached and had someone hit the starter to make sure they were firing as they should be.
Or you could spray a little starter fluid in the trottle boddy while someone cranks to see if it fires or not... isolate the issue to either fuel, air or fire would be my first step.
I dont know how often regulators go out, but it isnt unheard of. I personally would replace it while youre there...
My guess is you sucked crap up and either clogged the lines or regulator.
Glad you replaced them! Ive taken the fuel rail to the injectors off, leaveing the injectors attached and had someone hit the starter to make sure they were firing as they should be.
Or you could spray a little starter fluid in the trottle boddy while someone cranks to see if it fires or not... isolate the issue to either fuel, air or fire would be my first step.
I dont know how often regulators go out, but it isnt unheard of. I personally would replace it while youre there...
My guess is you sucked crap up and either clogged the lines or regulator.
09-28-2011, 09:56 PM
#3
1989 F150 4.9/300 5 speed
Thread Starter
Join Date: Jul 2011
Location: Raleigh, NC, USA
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
When i was making this thread I accidentally selected the title from my previous thread when it popped up as I was typing in the "title" field. I don't know how to delete this thread, but thanks for responding.
I re-posted with the title "1989 f150 4.9 Stalled and will not start."
I think you're right, it's a matter of isolating whether the problem is air, fuel or spark. I no-longer think the fuel lines are clogged. Even if chunks of material made it past the filter sock in the tank, it didn't clog the dual function reservoir and the next stop is the fuel filter, which would have certainly stopped it. I took the pressure regulator off tonight and it seems to hold gas just fine, meaning the diaphragm isn't damaged. Met another f150 owner that said the fuel pump should not be staying on constantly like mine. It should come on momentarily and then shut off. Can any of you confirm that with your working trucks?
I re-posted with the title "1989 f150 4.9 Stalled and will not start."
I think you're right, it's a matter of isolating whether the problem is air, fuel or spark. I no-longer think the fuel lines are clogged. Even if chunks of material made it past the filter sock in the tank, it didn't clog the dual function reservoir and the next stop is the fuel filter, which would have certainly stopped it. I took the pressure regulator off tonight and it seems to hold gas just fine, meaning the diaphragm isn't damaged. Met another f150 owner that said the fuel pump should not be staying on constantly like mine. It should come on momentarily and then shut off. Can any of you confirm that with your working trucks?
10-03-2011, 11:54 PM
#5
1989 F150 4.9/300 5 speed
Thread Starter
Join Date: Jul 2011
Location: Raleigh, NC, USA
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Update;
I put it all back together yesterday, and it didn't start immediately. Fuel pressure was reading around 20psi, so I exchanged the fuel pressure gauge set at Harbor Freight and it turns out it WAS broken. The new one shows me I'm at 55-56psi. Tonight, after some trying, IT STARTED UP AND RAN...roughly for 30 seconds while I had my foot on the accelerator. The running psi was much lower, I think 40ish, which the Haynes (i was wrong, it is a Haynes, not a Clymer) manual says it should be between 45 and 60psi. When I slowly let off the gas, it stalled and won't come back on. Gas pump continues to stay on all the time. Can I get any other confirmations out there? Just walk out to your EFI truck and turn the key to the on position and listen to how long your pump comes on. It would be a great help. If the pump is supposed to cut off quickly, could that be the pump relay in the fuse box?
I put it all back together yesterday, and it didn't start immediately. Fuel pressure was reading around 20psi, so I exchanged the fuel pressure gauge set at Harbor Freight and it turns out it WAS broken. The new one shows me I'm at 55-56psi. Tonight, after some trying, IT STARTED UP AND RAN...roughly for 30 seconds while I had my foot on the accelerator. The running psi was much lower, I think 40ish, which the Haynes (i was wrong, it is a Haynes, not a Clymer) manual says it should be between 45 and 60psi. When I slowly let off the gas, it stalled and won't come back on. Gas pump continues to stay on all the time. Can I get any other confirmations out there? Just walk out to your EFI truck and turn the key to the on position and listen to how long your pump comes on. It would be a great help. If the pump is supposed to cut off quickly, could that be the pump relay in the fuse box?
10-04-2011, 01:26 AM
#6
Old Bastard
Sean, Yes, you pump should shut off after a few seconds.
Your spark plugs have a story to tell you. You need to learn how to read that story.
Start here ---> http://www.ngksparkplugs.com/tech_su...qs/faqread.asp
Your spark plugs have a story to tell you. You need to learn how to read that story.
Start here ---> http://www.ngksparkplugs.com/tech_su...qs/faqread.asp
10-05-2011, 11:19 AM
#7
1989 F150 4.9/300 5 speed
Thread Starter
Join Date: Jul 2011
Location: Raleigh, NC, USA
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the confirmation that the fuel pump should only come on momentarily!
I'm going to check the manual for fuse info. I checked all the fuses first and I seem to remember there being a round shaped thing, a relay perhaps, that had something to do with the fuel pump? Since the pump isn't turning off, that's my first uneducated guess. The spark plugs certainly do have something to tell me, but I can't find pics that resemble the two that have identical deposit build ups. I think they came from the two cylinders in the middle. The closest thing I have seen to what I have is lead deposit build up, but nothing as extreme as what I had. Also, I found it interesting that when i chipped away at some of the deposit, chunks of it seemed to have a directional "grain" that resembles something crystals would form. I'm puzzled.
I'm going to check the manual for fuse info. I checked all the fuses first and I seem to remember there being a round shaped thing, a relay perhaps, that had something to do with the fuel pump? Since the pump isn't turning off, that's my first uneducated guess. The spark plugs certainly do have something to tell me, but I can't find pics that resemble the two that have identical deposit build ups. I think they came from the two cylinders in the middle. The closest thing I have seen to what I have is lead deposit build up, but nothing as extreme as what I had. Also, I found it interesting that when i chipped away at some of the deposit, chunks of it seemed to have a directional "grain" that resembles something crystals would form. I'm puzzled.
Last edited by SeanAA; 10-09-2011 at 12:00 AM. Reason: realized I was unclear
Trending Topics
10-05-2011, 01:29 PM
#8
Old Bastard
If your pumps are running, your fuses and all wiring to the pumps is good. Try pulling your fuel pump relay. Your pump should stop running.
Your computer tells the pump when to run. It does so because it recieves a signal form the TFI module that the engine is running. This is a very simplified explanation just to give you an idea.
The very first thing you should do is Check for codes. We should always start with our on board diagnostics.
Your computer tells the pump when to run. It does so because it recieves a signal form the TFI module that the engine is running. This is a very simplified explanation just to give you an idea.
The very first thing you should do is Check for codes. We should always start with our on board diagnostics.
10-06-2011, 12:05 AM
#9
1989 F150 4.9/300 5 speed
Thread Starter
Join Date: Jul 2011
Location: Raleigh, NC, USA
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Just getting in from working outside all day and I'm beat...Thanks, that makes a lot of sense. So, even though the check engine light doesn't come on, I could still have codes to read? That would be helpful. I found a link on this forum earlier for this reader...seems like a great deal. The code key is in my Haynes repair manual too.
Equus Innova 3145 OBD-I Ford Scan Tool
Okay, went outside to tinker with what I thought was the fuel pump relay (that round thing in the fuse box under the dash turned out to be related to the turn signals...)
I tried to turn it on and it started again, but the idle was loping hard and the check engine light came on for the first time. I gave it some gas to try and warm it up since my friend told me his truck had loping idle until it warmed up. After a few seconds of that, I let the off the gas pedal reeaaaally slowly so it wouldn't stall like it did last time. When I got back down to an idle, it was still loping just as badly. I went around to disconnect the trickle charger from the battery to try and run a lap around the storage facility (where I work and live) and noticed the trickle charger was turning on and off with the loping, as well as the interior light. The alternator is a freshly rebuilt one from Advance Auto a couple months back and the battery is new from the previous owner, but smaller than the OEM. There was also a loud vacuum noise coming from the PVC valve I replaced when I removed the injectors for cleaning. The PVC that Auto Zone gave me had two different size nozzles to attach vacuum hoses, but I just thought it had something to do with being a universal part. Turns out they probably gave me the wrong one, because it was sucking air in hard from the unused nozzle. When I covered it the engine stalled instantly. I swapped it out with my old one and the truck wouldn't start. I put the 2 nozzle PVC back and it started up again with the loping. Mean anything to you? Because it doesn't to me yet...
Equus Innova 3145 OBD-I Ford Scan Tool
Okay, went outside to tinker with what I thought was the fuel pump relay (that round thing in the fuse box under the dash turned out to be related to the turn signals...)
I tried to turn it on and it started again, but the idle was loping hard and the check engine light came on for the first time. I gave it some gas to try and warm it up since my friend told me his truck had loping idle until it warmed up. After a few seconds of that, I let the off the gas pedal reeaaaally slowly so it wouldn't stall like it did last time. When I got back down to an idle, it was still loping just as badly. I went around to disconnect the trickle charger from the battery to try and run a lap around the storage facility (where I work and live) and noticed the trickle charger was turning on and off with the loping, as well as the interior light. The alternator is a freshly rebuilt one from Advance Auto a couple months back and the battery is new from the previous owner, but smaller than the OEM. There was also a loud vacuum noise coming from the PVC valve I replaced when I removed the injectors for cleaning. The PVC that Auto Zone gave me had two different size nozzles to attach vacuum hoses, but I just thought it had something to do with being a universal part. Turns out they probably gave me the wrong one, because it was sucking air in hard from the unused nozzle. When I covered it the engine stalled instantly. I swapped it out with my old one and the truck wouldn't start. I put the 2 nozzle PVC back and it started up again with the loping. Mean anything to you? Because it doesn't to me yet...
Last edited by SeanAA; 10-06-2011 at 12:07 AM.
10-06-2011, 12:49 AM
#10
Old Bastard
First things first.
Pull the Alternator and the Battery and take them to Advance and have them tested. Only a Major short will pull them down enough to kill the lights and cause the engine to stumble. Right off the back I suspect a cell in the battery is shorting out. Just a guess, because I am not there. There will be a voltage drop with the engine RPM change, but it should not drop below 12.6V. Get a Voltmeter on it.
If a vacuum leak makes it run better, then it is starving for air. You can cap that unused port. It is not the wrong one, just a different design. Pull your intake loose and see if your idle improves.
Again I am guessing. The most important thing you can do at this point is get the codes, and you don't need a reader: ----> https://www.f150forum.com/f10/how-re...es-obdi-10907/ (Tip: Use a Test light in place of the meter, count the flashes) and get a repair manual. I like Haynes if you can't find a Ford Shop Manual. That will be the best $25 you'll spend on your truck.
Pull the Alternator and the Battery and take them to Advance and have them tested. Only a Major short will pull them down enough to kill the lights and cause the engine to stumble. Right off the back I suspect a cell in the battery is shorting out. Just a guess, because I am not there. There will be a voltage drop with the engine RPM change, but it should not drop below 12.6V. Get a Voltmeter on it.
If a vacuum leak makes it run better, then it is starving for air. You can cap that unused port. It is not the wrong one, just a different design. Pull your intake loose and see if your idle improves.
Again I am guessing. The most important thing you can do at this point is get the codes, and you don't need a reader: ----> https://www.f150forum.com/f10/how-re...es-obdi-10907/ (Tip: Use a Test light in place of the meter, count the flashes) and get a repair manual. I like Haynes if you can't find a Ford Shop Manual. That will be the best $25 you'll spend on your truck.
Last edited by kc0rey; 10-06-2011 at 12:52 AM.