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fordnut
New User
Jul 15, 2011, 1:52 AM
Post #1 of 12
(2171 views)
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86 f 150 5.0 fi.4 spd.engine has slight hesitation and speratic back fire thru intake at low rpm.changed plugs,wires,cap,rotor,pcv,set timing at 10 btdc
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 5:56 AM
Post #2 of 12
(2156 views)
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Does this backfire on acceleration? Have you checked fuel pressure with a fuel pressure test gauge? (27-37 psi engine running) Checked for vacuum leaks? Have you done a TPS voltage sweep?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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zmame
Veteran
/ Moderator
Jul 15, 2011, 8:57 PM
Post #3 of 12
(2149 views)
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did this happen befor you set the timing??.. I belive in that year you had to disconnect a jumper inorder to set the timing properly.. looks like a square plastic block hooked to 2 wires some where around the disributor. Mark the 10 btdc with are paint marker on the flywheel so you can see it well with a timing light.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 9:40 PM
Post #4 of 12
(2147 views)
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Thoughts etc: How far off was the timing and why? If and especially if this has the original timing chain w nylon cam gear bet it's jumped. I'd rule it out anyway @ 25 years old unless known replaced and good. Just once saw the roll pin shear on distributor also.
See if pic shows...........
Nope - here's a link to what you might find........ http://t1.gstatic.com/...c9IKacdpy-iA&t=1
I tried to make pic show up here but it didn't work
T
(This post was edited by Hammer Time on Jul 16, 2011, 3:16 AM)
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zmame
Veteran
/ Moderator
Jul 15, 2011, 9:52 PM
Post #5 of 12
(2141 views)
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good point tom.. although if you didn't pull the jumper out when you initally checked it his reading will be wrong.. it may have been right all along
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 10:04 PM
Post #6 of 12
(2138 views)
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Look back I was working on a pic that didn't work. Not just Ford but damn nylon doesn't age well and can either crack up like glass or plain wear thin. Owned my share of 5.0s - none in trucks but same idea. Old V8 Pontiacs took the cake for these, even the replacements!
True about the little jumper block thingy too......
T
(This post was edited by Tom Greenleaf on Jul 15, 2011, 10:09 PM)
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zmame
Veteran
/ Moderator
Jul 15, 2011, 10:18 PM
Post #7 of 12
(2133 views)
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yes nylon coated gears stupid idea.. they sell billet aftermarket ones.. it's very unclear in that era what 5.0L used them and which ones didn't seems like 1/2 did and 1/2 didn't :/.. think the 300-6 used them too in some years. wouldn't be bad to inspect it anyways with little bit of work.
found picture of a bad one 140k miles
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 10:31 PM
Post #8 of 12
(2132 views)
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I'm not judge or jury for doing this but it sure was stupid or corrupt. Heard once it was so they would be quieter. ARE YOU SH!TTING ME? They all metal replacements didn't make a peep
All of the "Big Three" did this trick resulting in even wear to no teeth, chunks missing, or several in a row snapped off. Oddly many ran great right up to quitting time without much notice. On difficult or fussy water pumps I'd always ask a customer if they wanted to go one step further as that was most of the way there to get rid of an original.
Oh ya, let's bail out the bastards,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 10:40 PM
Post #9 of 12
(2129 views)
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I've haven't seen the effects of not removing the SPOUT when setting timing. I have an 88 Mustang sitting the garage. Could experiment and see if it mimics the OP's symptoms. I gotta pull the timing cover off anyway today for the leaking gasket.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 10:42 PM
Post #10 of 12
(2127 views)
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They were quieter...especially when the chain fell off 
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2011, 10:46 PM
Post #11 of 12
(2120 views)
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Keyboard just got destroyed blowing coffee all over it! Good one,
Tom
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zmame
Veteran
/ Moderator
Jul 15, 2011, 10:51 PM
Post #12 of 12
(2116 views)
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it does make a difference if you do it right.
Warm up the engine
shut engine off
then pull spout connector
re-start vechical
if you have a decent snap on timing light you can just paint the TDC line , line it up with marker then set timing light to 10 BTDC.
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