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Discussion Starter #1
Hello everyone. Just got off the phone with the mechanic. He said number 6 and 8 cylinders weren't firing. He said the sparkplugs are good And even switched them out with new ones. They have spark. Then he tested the fuel injectors. They work. He did a compression test and it has compression. So now the question is if its getting fuel and spark why wouldn't it fire. I'm stumped. Any ideas would be appreciated
 

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Charlie don't surf..
'92 Ford Bronco XLT
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you said he tested the fuel injectors, but did he check the injector harness?
 

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yo eskiltell,

Can you please clarify what the mechanic said to you?
Here is what I see;
Fuel injectors work
Number 6 and 8 cylinders weren't firing.
New spark plugs have spark

"...So now the question is if its getting fuel and spark why wouldn't it fire. I'm stumped..."
So am I - when he said it won't fire, why did he state that 6 & 8 weren't firing?
 

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The air and fuel mixture has to be able to get in and out of the cylinder. Sounds like if what you (and the mechanic) said is true, the valves would be my next check. They may not be opening.
 

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The air and fuel mixture has to be able to get in and out of the cylinder. Sounds like if what you (and the mechanic) said is true, the valves would be my next check. They may not be opening.
are plug wires crossed somewhere

or maybe worn out cam
 

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Discussion Starter #6
Not sure how he figured it out. He said he moved plugs from cylinders that were firing and they still wouldn't work. I don't think its the wires. They're brand new. If the valves were stuck then wouldn't the compression test fail? I was thinking a blown head gasket but it would be strange if it only busted around those two cylinders. I'll update everyone tomorrow when he calls me again. At least a remanufactured motor doesn't cost thousands of dollars!!!!!
 

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yo e,

This is by Ford so you know what can be excluded;
Compression Readings — Interpreting
It is recommended the Compression Pressure Limit Chart be used when checking cylinder compression so that the lowest reading number is 75 percent of the highest reading.
If one or more cylinders reads low, squirt approximately one 1.5 ml (1 tablespoon) of SAE 50 weight or equivalent engine oil on top of the pistons in the low reading cylinders. Repeat compression pressure check on these cylinders.
1.If compression improves considerably, piston rings are at fault.
2.If compression does not improve, valves are sticking or seating poorly.
3.If two adjacent cylinders indicate low compression pressures and squirting oil on pistons does not increase compression, cause may be a cylinder head gasket leak between cylinders. Engine oil and/or coolant in cylinders could result from this problem.
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In case anyone suggests a reman engine, get back to us here.
Consider Ford Remanufactured Transmissions & Engines - Motorcraft® Brand, Broncos & all Ford
Halli wrote on 30 DEC 2010 that for a Ford Reman 5.8l long block it is 2308.00 exchange. 2210.00 for a 5.0; These are Ford dealer prices in the Mid-South
Reman 5.0 = $1914.56

JR Nice wrote on 5 MAY 2012, Ford crate 5.0 H.O was about $1900. My local rebuild on my 5.8 was about $2300.
radiolotek wrote on 19 May 2012, $2300. For a complete assembly (1995 5.8)

Here is Ford's reman site http://www.fordinstallersupport.com/files/catalogs/ptm200.pdf

Here is latest RETAIL price from Ford Parts on-line; see if local dealer will discount.
http://www.fordparts.com
 

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aka: kemicalburns
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I think we need to ask what caused you to take the rig to the mechanic to begin with? how many miles are on the motor and what was the comp test results from the mechanic?

what plugs and plug wires are being used? has the cap and rotor been replaced? If the park plug wires are touching/crossing there could be misfire occurring. how familiar is this guy with Ford EFI? does he realize its batch fired?
 

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I think we need to ask what caused you to take the rig to the mechanic to begin with?
:stupid

Does the engine run??

I'd ask to see a timing light hooked to each of the wires to verify what is being said. If they truly aren't firing, then the timing light won't light. I find this to be a strange diagnoses that 6 & 8 aren't firing.
 

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Discussion Starter #10
I think we need to ask what caused you to take the rig to the mechanic to begin with? how many miles are on the motor and what was the comp test results from the mechanic?

what plugs and plug wires are being used? has the cap and rotor been replaced? If the park plug wires are touching/crossing there could be misfire occurring. how familiar is this guy with Ford EFI? does he realize its batch fired?
I brought it there after about a week and a half of trying to get her running without after fire through the intake. After awhile I was just doing the same checks over and over so I just quit and said its going to the mechanic. The plugs and wires were just average O'Reillys stuff. Not top dollar but not the cheapest. I've been building Chevy motors for quite some time and I've never had a problem with wires touching. I would figure that to be a problem after years of wires degrading. I'm going to head over there later today and see what's going on.

As for new motors I found ones for 800 and some change.
 

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I brought it there after about a week and a half of trying to get her running without after fire through the intake. After awhile I was just doing the same checks over and over so I just quit and said its going to the mechanic.
A fire through the intake tells me that either it wasn't wired up properly (Fords cylinders patterns are different from Chebys), or you have burn't or bent valves. But if the compression numbers are good, then the valve issue is probably not it. Which leads me to believe that it's wired incorrectly.

Did it run before you put the new wires on??
 

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Discussion Starter #12
A fire through the intake tells me that either it wasn't wired up properly (Fords cylinders patterns are different from Chebys), or you have burn't or bent valves. But if the compression numbers are good, then the valve issue is probably not it. Which leads me to believe that it's wired incorrectly.

Did it run before you put the new wires on??
He said it's wires correctly.

Here's the new motor I found. http://www.carmonkeys.com/1991-FORD-BRONCO-Engine-Assembly-5-8L-VIN-H-8th-Digit-8-351W-5-Years-Warranty?utm_campaign=google

Not sure if I can replace it without removing the trans.
 

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aka: kemicalburns
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a new motor wont fix this sort of issue I don't believe. are you saying that you where getting backfire thru the intake? if so then your dealing with a timing issue or perhaps the timing chain jumped a tooth.
 
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