Need some help
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Need some help
I have a 86 F150 with a 351. I haven't driven it in awhile so last week started driving it again. It has been running rough and I thought I might need to put some gas treatment in. Didn't get to it yesterday and when I went out to start it this morning the engine rotates but it won't start. There is no gas smell so I am thinking fuel pump. I have duel fuel tanks and it won't start with either one. Does it sound like a fuel pump or maybe an electric problem? Do fuel pumps just suddenly go out? I noticed when I start it first thing this last week it started up fine, but when I killed it and then tried to start it 30 minutes later it acted like it didn't want to start up. Trying to fix it myself and avoid towing fees and mechanics charges.
Tuned
Joined: Oct 2003
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I'd check and see if you had fire to the plugs.......
Then maybe disconnect the fuel line, and crank the truck........
There is some basic troubleshooting that needs to be done in order to identify the problem.
There was a good troubleshooting section in the front of the old chilton's manual.
Then maybe disconnect the fuel line, and crank the truck........
There is some basic troubleshooting that needs to be done in order to identify the problem.
There was a good troubleshooting section in the front of the old chilton's manual.
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Fuel pumps have a 2 second time unless the engine starts.
when it is Quiet
Get under the truck and have someone turn the key to run..you should be able to hear the pumps.
Welcome to FTE !
Oh btw, for future threads ..please put the actual Topic in the title. we are already here to help.
when it is Quiet
Get under the truck and have someone turn the key to run..you should be able to hear the pumps.
Welcome to FTE !
Oh btw, for future threads ..please put the actual Topic in the title. we are already here to help.
Junior User
Joined: Feb 2007
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From: Florida
There is also a high pressure fuel pump on the frame rail as well as the 2 pumps in the tanks. Get a fuel guage and check pressure on the fuel rail if you have already checked for spark. The place to check pressure looks like the valve stem on a tire. I never used a guage, but just pushed the valve stem in, but that is up to you a guage is reccommended.
Mike
Mike
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From: Virginia
Originally Posted by MikeFlorida
There is also a high pressure fuel pump on the frame rail as well as the 2 pumps in the tanks. Get a fuel guage and check pressure on the fuel rail if you have already checked for spark. The place to check pressure looks like the valve stem on a tire. I never used a guage, but just pushed the valve stem in, but that is up to you a guage is reccommended.
Mike
Mike
If it is carbed, take the aircleaner off, and while looking down the carb throat, push back the throttle. You should have two strong streams of gas pouring in. If you don't you definitely have a fuel problem.
Last edited by Franklin2; Mar 16, 2007 at 11:41 AM.
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I do have a carbed truck with a holly carb on it. I am hoping to get to it this weekend to see what is going on. Thanks for the info you've sent my way. I also know that I have a low pressure fuel pump in each of my gas tanks, would they both go out at the same time or usually just one? The only reason I was thinking fuel problem is when I attempt to start it there is no gas smell that you get when you flood a vehicle. This last week it was okay to start from a cold start but once it got hot it was hard to get started. It is finicky to say the least so I was just thinking before it stopped working that I just needed a gas treatment and to run out the old gas. Like I said in my first post it had been sitting for awhile and only driven every once in awhile. If there is no gas stream then I will start with my inline fuel filter, maybe I'll get lucky and it will be the fuel filter.
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From: Virginia
I am not too familiar with your fuel setup, but it sounds like the same setup used on the 460's.
The carbed 460 had electric fuel pumps in the tanks, with a fuel return line at the carb. In that system, they had a fuel pump relay that sent power to the fuel switch in the dash, and the switch selected which fuel pump came on, and also told the valve on the frame rail to switch the fuel lines and the sending units.
When you were cranking the engine the 460 system sent power to the fuel relay by way of the starter solenoid to prime the system. Once started, the fuel pump relay was fed power through a oil pressure switch on the engine. This was for safety, in case the engine stalled, it would kill the fuel pumps.
The carbed 460 had electric fuel pumps in the tanks, with a fuel return line at the carb. In that system, they had a fuel pump relay that sent power to the fuel switch in the dash, and the switch selected which fuel pump came on, and also told the valve on the frame rail to switch the fuel lines and the sending units.
When you were cranking the engine the 460 system sent power to the fuel relay by way of the starter solenoid to prime the system. Once started, the fuel pump relay was fed power through a oil pressure switch on the engine. This was for safety, in case the engine stalled, it would kill the fuel pumps.
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Well I have fuel going to the carb, had the ignition module tested said it was good, the coil appears to be good. Stupid question coming though, how can I check my spark plugs for fire? I read about a calibrated ignition tester but can't find one. I know according to specs my ignition system is a Duraspark II. I pulled a spark plug and it was sooty but I already knew it was running rich. Any help or input would be appreciated. I guess I should have paid more attention to my grandpa in his shop.
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Forgot to mention sprayed starter fluid down the carb and tried to start still no start. Can I rule out fuel problem and concentrate on ignition problem? Really want to take care of it myself if at all possible. My father in law will be here on the 26th hopefully he can help.
Lead Driver
Joined: Dec 2002
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From: Kuna ID
There are 2 ways you can check for spark, the cheap way is to remove a plug, reconnect the wire and hold it against the block while someone cranks the motor and you watch for a spark. You can also buy an inline tester. They are pretty cheap, less that $10 I think. You disconnect the plug wire, put the tester on the plug and then connect the plug wire to the tester. IT has a clear middle section so you can see the spark crossing(if you have one) while someone is cranking the truck. It's a little safer too, you can get quite a jolt if you hold the plug wrong doing it the other way.
Tuned
Joined: Oct 2003
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You can remove a plug and set in on the intake......crank the engine and see if it fires.
If you have an induction type timing light, hook it up and see if the light fires.
Don't hold the wire or you might get a shock.....come to think of it, that might be a way to test it lol.
If you have no spark at the plug you could possibly have a missing +12 at the primary side of the coil....so your starter turns, but no power to the coil....or other ignition problems.
If you have fuel, and have fire, then all you need is to have them at the right time.
Have you removed the distributer cap and inspected the contacts and rotor button?
If you have an induction type timing light, hook it up and see if the light fires.
Don't hold the wire or you might get a shock.....come to think of it, that might be a way to test it
lol.If you have no spark at the plug you could possibly have a missing +12 at the primary side of the coil....so your starter turns, but no power to the coil....or other ignition problems.
If you have fuel, and have fire, then all you need is to have them at the right time.
Have you removed the distributer cap and inspected the contacts and rotor button?
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Can i use the inline tester even if the engine won't run? Did check the distributor cap and the rotor button and all looks really clean and there is tension on the rotor button. I put a new coil on it but wondering if it could be the assembly that runs from the coil to the top of the distributor. According to my wiring diagram I should have a stator in the distributor. Also if it were the fuel filter would I still be getting a good stream of fuel into the carb? Ofginally I was thinking fuel filter but now I don't know.
Lead Driver
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From: Kuna ID
Yeah, it's just a window to watch the spark pass through. It helped me find a problem I had with a dodge. I had spark but it was intermittent, due to a bad cap/rotor. They looked good, but just weren't making consistent contact. If you have no spark, there is a part inside the distributor that can go bad and kill your spark.
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