No Guts
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
No Guts
This page shows how to make your own air/fuel meter to tune a carb, but I prefer a vacuum gauge.
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New User
Joined: Nov 2002
Posts: 15
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From: Clearfield
No Guts
[Wkato: have you checked manifold vacuum yet?
Robert, No have not check manifold vacuum yet, what is the best way to go about it?
Steve83 the truck is Fuel Injected so carb tuning will not help. Thanks
Mustanggt221, I don't have a 4.10s and 31" tires. I have 3.55 average size tires.
Duderoy, "air/fuel ratio gauge" I think this was checked by the shop but not sure. How do you go about checking this?
wkato
Robert, No have not check manifold vacuum yet, what is the best way to go about it?
Steve83 the truck is Fuel Injected so carb tuning will not help. Thanks
Mustanggt221, I don't have a 4.10s and 31" tires. I have 3.55 average size tires.
Duderoy, "air/fuel ratio gauge" I think this was checked by the shop but not sure. How do you go about checking this?
wkato
Senior User
Joined: May 2003
Posts: 203
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From: San Diego
No Guts
Buy a vucuum guage from any auto parts store along with a short piece of vacuum hose, size determined by:
Locate the vacuum tree on top of the intake manifold. The hose on top farthest forward should be capped (manual trans) or has a hose (auto trans). Pull the hose and measure the nipple. Mine is 5/16, but it probably varies according to engine. Nipple placement also might vary with engine.
Pull the hose and attach the vacuum guage with a short (6" max) piece of hose. Start the engine, let idle. After the idle drops down, you should read around 20" vacuum. If under 20", it should only be barely under. If way under, find the leak.
Regards, Robert.
Locate the vacuum tree on top of the intake manifold. The hose on top farthest forward should be capped (manual trans) or has a hose (auto trans). Pull the hose and measure the nipple. Mine is 5/16, but it probably varies according to engine. Nipple placement also might vary with engine.
Pull the hose and attach the vacuum guage with a short (6" max) piece of hose. Start the engine, let idle. After the idle drops down, you should read around 20" vacuum. If under 20", it should only be barely under. If way under, find the leak.
Regards, Robert.
Post Fiend
Joined: Nov 2001
Posts: 14,947
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From: Topsfield, MA
No Guts
Originally posted by Robert at the Beach
'88 302 F250 4x4, 4.10 ls rear end, 5sp manual, 31" Duelers will tow my wimpy #2500 boat around like it (almost) isn't even there, even up moderate grades in 5th, but then I keep it under 65 when towing, too.
Minimal strain on the drivetrain means this rig should be around for a good long time.
Wkato: have you checked manifold vacuum yet?
Regards, Robert.
'88 302 F250 4x4, 4.10 ls rear end, 5sp manual, 31" Duelers will tow my wimpy #2500 boat around like it (almost) isn't even there, even up moderate grades in 5th, but then I keep it under 65 when towing, too.
Minimal strain on the drivetrain means this rig should be around for a good long time.
Wkato: have you checked manifold vacuum yet?
Regards, Robert.
I was refering to what Robert said, sorry.
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New User
Joined: Nov 2002
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From: Clearfield
No Guts
Robert, Thanks for the manifold info, will get a vacuum guage and check into it hopefully this week.
Mustang, sorry back to ya. The post have gone in different direction and got a bit confusing.
wkato
Mustang, sorry back to ya. The post have gone in different direction and got a bit confusing.
wkato
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New User
Joined: Nov 2002
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From: Clearfield
No Guts
Ok did the manifold vacuum test, had a steady 16 hg. Looked it up in my Hayes book only thing related was a flow restriction check and it said anything 16 and above was good. Also took it to 2000 RPM for one minute per book and it held constant 16 vacuum but ran alittle ruff.
Any thoughts?
wkato
Any thoughts?
wkato
Senior User
Joined: May 2003
Posts: 203
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From: San Diego
No Guts
16 in vacuum on a 302 isn't even close to enough. The 5.8 may be different, but 16in sounds way low.
Pull and plug each vac line on the tree and check the vacuum. Does it jump to 20" when any one of them is off?
If not, check all around the manifold with the wet/dry vac hose and crevice tool test, or the WD-40 test. You have to have a vacuum leak there somewhere.
Regards, Robert.
Pull and plug each vac line on the tree and check the vacuum. Does it jump to 20" when any one of them is off?
If not, check all around the manifold with the wet/dry vac hose and crevice tool test, or the WD-40 test. You have to have a vacuum leak there somewhere.
Regards, Robert.
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Brett Foote
Senior User
Joined: May 2003
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From: San Diego
No Guts
The 2" wet/dry vac hose (standard size) is used with the 2" end to your phone ear, and the crevice tool on the other end. Point the crevice tool CAREFULLY! BEWARE OF ENGINE FAN! around the base of the intake manifold and listen for hissing, as in air sucking through a small opening in the gasket area. Check all around and see if you can find a vacuum leak.
OR
Spray around with WD40, just a squirt at a time, the intake manifold gasket, throttle body gasket, et all, and listen for slight increases in rpm. The increases are very quick and only 100 rpm or so, but if you get any, you have a vacuum leak there. Pull off the hoses to the throttle body and give it a squirt so you know what to listen for. Then put the hoses back on and do the test.
Hope this helps, Robert.
OR
Spray around with WD40, just a squirt at a time, the intake manifold gasket, throttle body gasket, et all, and listen for slight increases in rpm. The increases are very quick and only 100 rpm or so, but if you get any, you have a vacuum leak there. Pull off the hoses to the throttle body and give it a squirt so you know what to listen for. Then put the hoses back on and do the test.
Hope this helps, Robert.
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New User
Joined: Nov 2002
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From: Clearfield
Never posted the follow up!
No help from Ford! Said the truck is running fine and they couldn't find anything wrong. Kind of p's me off cause I know there is, I feel the problem everyday. Even when not pulling I can feel it on hills.
Wes
No help from Ford! Said the truck is running fine and they couldn't find anything wrong. Kind of p's me off cause I know there is, I feel the problem everyday. Even when not pulling I can feel it on hills.
Wes
Elder User
Joined: Apr 2004
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From: everywhere and nowhere
did you ever try to find out if you had a vacuum leak? had the same problem with my 87 250, 5.8, c6, 3.88 rear, couldnt figure out why it was hesitatin, and had absoultely no power, found a number of vacuum leaks on it, plugged them, and havent had a problem since
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Well if the motor checks out good how about the transmission that will rob power if worn or has never seen a lube change.
Could be your brakes binding. How do the wheels rotate of the ground, check everything something is causing a drag somewere.
Mike
Could be your brakes binding. How do the wheels rotate of the ground, check everything something is causing a drag somewere.
Mike