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1986 F150 5.0 hard to start,will not idle

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85lebaront2

Re: 1986 F150 5.0 hard to start,will not idle

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This post was updated on .

Gee, I remember that headache. I spent a weekend in Falling Waters WV getting it solved.

Maybe Gary could add that into the idle setting information.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

1986 F150

Re: 1986 F150 5.0 hard to start,will not idle

In reply to this post by 85lebaront2

85lebaront2 wrote

Jeff, Jim, the 1985/86 5.0L EFI system is not like the 1987 up systems, The idle stop screw setting is very touchy on these. The EGR system starts to function just off idle (Matt's drove both of us nuts). In the right front corner behind the battery is a set of solenoid valves:

Two of them are for the EGR valve, the other two are for the Thermactor system. If the TPS voltage is too high, the EGR pair will chatter and the EGR valve will try to open, which kills the idle, followed by closing where it will pick up again.

The idle may be raised to get around this. One item we did discover, aftermarket sensors do not always react the same as OEM Ford ones, he had a Standard TPS and could not get the closed throttle voltage low enough. A Motorcraft one solved the problem.

I did not hear any chattering from the EGR solenoid valves. I'll do a voltage check on the TPS. I just can't see the TPS suddenly going out, as like I mentioned before, it idled in gear fine before I replaced a bad TFI module (I had it tested and it was shot). I don't know what else to try, am getting close to the end of my rope. Can't afford to dump much more money into it

Jeff
Abilene Ks

1986 F150 XLT Lariat 4x2 standard cab 5.0 AOD
1989 E150 conversion van 4.9 C6

ArdWrknTrk

Re: 1986 F150 5.0 hard to start,will not idle

Administrator

I'm never about parts swapping and always about diagnosis.
Take some readings from the TPS and if it's out of range slack off the the stop to see if you can get it back where it belongs.

The fuel regulator was obviously a big issue that needed replaced before any other trouble shooting.
You might find closing the plate up will help since there's not gas going everywhere now.

Do you have an accurate meter?

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

1986 F150

Re: 1986 F150 5.0 hard to start,will not idle

ArdWrknTrk wrote

I'm never about parts swapping and always about diagnosis.
Take some readings from the TPS and if it's out of range slack off the the stop to see if you can get it back where it belongs.

The fuel regulator was obviously a big issue that needed replaced before any other trouble shooting.
You might find closing the plate up will help since there's not gas going everywhere now.

Do you have an accurate meter?

I have a digital multimeter I bought from a tool bin at my local hardware store a few years ago, it's as accurate as it can be I guess, it'll have to do.

Jeff
Abilene Ks

1986 F150 XLT Lariat 4x2 standard cab 5.0 AOD
1989 E150 conversion van 4.9 C6

ArdWrknTrk

Re: 1986 F150 5.0 hard to start,will not idle

Administrator

Digital is good as long as the battery is fresh.
Let us know what you find!

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

grumpin

Re: 1986 F150 5.0 hard to start,will not idle

In reply to this post by 1986 F150

1986 F150 wrote

85lebaront2 wrote

Jeff, Jim, the 1985/86 5.0L EFI system is not like the 1987 up systems, The idle stop screw setting is very touchy on these. The EGR system starts to function just off idle (Matt's drove both of us nuts). In the right front corner behind the battery is a set of solenoid valves:

Two of them are for the EGR valve, the other two are for the Thermactor system. If the TPS voltage is too high, the EGR pair will chatter and the EGR valve will try to open, which kills the idle, followed by closing where it will pick up again.

The idle may be raised to get around this. One item we did discover, aftermarket sensors do not always react the same as OEM Ford ones, he had a Standard TPS and could not get the closed throttle voltage low enough. A Motorcraft one solved the problem.

I did not hear any chattering from the EGR solenoid valves. I'll do a voltage check on the TPS. I just can't see the TPS suddenly going out, as like I mentioned before, it idled in gear fine before I replaced a bad TFI module (I had it tested and it was shot). I don't know what else to try, am getting close to the end of my rope. Can't afford to dump much more money into it

You said you replaced the TFI Module. It could be bad out of the box. Can't trust aftermarket parts anymore. I'd be leary of OEM anymore.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

1986 F150

Re: 1986 F150 5.0 hard to start,will not idle

In reply to this post by ArdWrknTrk

ArdWrknTrk wrote

Digital is good as long as the battery is fresh.
Let us know what you find!

TPS test results: 5 volts between orange wire and black wire
1 volt between dark green wire and black wire

Jeff
Abilene Ks

1986 F150 XLT Lariat 4x2 standard cab 5.0 AOD
1989 E150 conversion van 4.9 C6

ArdWrknTrk

Re: 1986 F150 5.0 hard to start,will not idle

Administrator

More good news!

I might try to back the idle down to see if that keeps the transmission from loading the engine in gear.

Curb idle for automatics is shown in gear (with the vacuum advance capped and wheels chocked) on the emissions/vacuum sticker attached to the radiator support.
But you might look to the 'manual in neutral' setting to get an idea of engine speed if you can't yet do it engaged in drive.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

vjsimone

Re: 1986 F150 5.0 hard to start,will not idle

In reply to this post by 1986 F150

1986 F150 wrote

ArdWrknTrk wrote

Digital is good as long as the battery is fresh.
Let us know what you find!

TPS test results: 5 volts between orange wire and black wire
1 volt between dark green wire and black wire

Hello Jeff, (following) how is this going ?

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"