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85 2.8 Idling too high


andyh13

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Warren, MI
Vehicle Year
1985
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Ford
Engine Type
2.8 V6
Transmission
Manual
2WD / 4WD
4WD
My '85 ranger was converted to duraspark/HEI by the previous owner, who also swapped out the feedback carb for a 2150.

I have been having a lot of trouble getting the truck to idle "nicely". It seems way too loud and fast, but screwing out the curb idle screw doesn't seem to be lowering the rpm. I don't have a tachometer to conclusively verify this, but there's no difference in the sound of the engine. I also hear a hissing noise from the engine bay. The mixture screws also don't seem to be having much effect either. I hooked up a cheap vacuum gauge, and the vacuum was very low. The pointer on the gauge was at an area labeled "valve timing/intake manifold leak".

I believe there's a vacuum leak, but I am not having any luck tracking it down with carb cleaner. As a control, I sprayed some carb cleaner straight down the carb intake. Only once I had sprayed a fair bit in there did it have any effect, and it slowed the engine down. Does this mean the air fuel mixture is already too rich?

I also tested the timing, and it was off. I turned the distributor to align a white mark on the belt (assuming this was set correctly) with the pointer at the bottom of the engine block, and the vacuum rose considerably. However, it is still quite a bit below the gauge's green area, and not even to the section of the gauge labeled "overly advanced timing" (not that I trust this gauge much).

I would like to test the intake manifold for leaks, but given the way the engine doesn't seem to respond much even when carb cleaner is sprayed straight into the intake, I am not confident this method will show me if there is a leak.

When I get home today, I plan on trying to turn the mix screws in as far as I can get them without losing vacuum, then spraying the carb cleaner again and seeing what happens.

If that doesn't work, I will probably try to rebuild the carburetor, but that's a significant undertaking for someone with my (very low) level of skill.

Does anyone here have other ideas about what might be going on? Does this sound like a reasonable approach to troubleshooting? Appreciate any input!
 


andyh13

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1985
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Manual
2WD / 4WD
4WD
I forgot to mention, I might also try blowing smoke into the vacuum port tree coming off the carb (just with a cheap cigar, I don't have a machine). Does anyone know if this would help find a leak in the intake manifold? Or is low pressure smoke not going to travel that far?

Thanks for any guidance!
 

andyh13

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1985
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Ford
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Transmission
Manual
2WD / 4WD
4WD
Here's a video of me blowing smoke up the PCV line.

I only notice this after checking the video, but it looks like there's a lot of smoke coming from behind the carb. I will investigate further tomorrow. Does anyone have an idea what this could be? I don't think it's the vacuum tree, and I thought I had all the ports on the back of the carb covered.
 

andyh13

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4WD
I found an unplugged vacuum port beneath the carburetor. It was pretty hard to find before I saw smoke coming out of it, but I feel pretty stupid for having missed it.

Plugging the port caused the engine to run quieter, but didn't increase the vacuum reading on my cheap gauge.

What's more: Since unmetered airflow was eliminated, I assumed the mixture was now too rich. I screwed in the fuel mixture screws until the engine started running less smooth (no loss of vacuum though, according to this gauge), then turned them back out a half turn. I pulled off the vacuum gauge, at which point the engine died,and plugged the port it was attached to. I put on the air cleaner and excitedly closed the hood and went to start up the car for a ride around the block, only to turn the key and get... cranking, but no start. Not even the starting then dying that I had been getting if the fuel mixture was too lean before. I tried backing the mix screws out a half turn at a time until they were maybe 4-5 turns out, and never had any luck.

I am pretty stumped about this. Perhaps I somehow flooded the engine? When I manually press the throttle on the carb, fuel sprays out. I can't think of how I would have lost compression, spark, or timing.

I will troubleshoot some more tomorrow. Unfortunately this "one step forward two steps back" thing seems to be my standard when working on this truck.

As always, if anyone reading this has suggestions I am all ears
 

litleblue

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2WD / 4WD
4WD
On the right hand side of the carb float bowel there is a circle with a number in it. It should be a 1.08 Venturi, if you have a 1.21 Venturi the carb is to large and the engine won’t run right. Go find the right carb.

Ford 2150 carbs come with ported vacuum. To find the connection take an air hose with about 30 psi of pressure and start applying pressure to the different ports. The port that blows air out of a small hole in the Venturi just above the throttle plate when it is shut is ported vacuum. This is the vacuum the distributor needs, Not Manifold Vacuum! Ported vacuum is velocity depended and follows the the load profile of the engine. Low load low rpm high vacuum, low load low rpm no vacuum etc.

Most other connections to operate vacuum accessory’s can come from the manifold vac. The only accessory you should have is the air charge and stove system and vacuum power breaks. The old eecIV system operated a plethora of systems, and it worked great.

By the way the hose you are blowing int is manifold vacuum and that usually hooks up to the power valve under the float bowl. The large leak on the back of the carb is where the PVC valve connection. The one on the right hand side I think went to the old carbon canister through a electric valve controlled by the EECIV computer plug this one off. Hook the other two up to the correct spots and then find the ported vac connection. Once you are finished set the base timing to about 15 to 20 deg before TDC at idle. If you aren’t getting above 21mpg on the highway at about 60 mph with stock tires 215 75 r15’s something is wrong.
 

andyh13

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Feb 5, 2018
Messages
15
Reaction score
1
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Location
Warren, MI
Vehicle Year
1985
Make / Model
Ford
Engine Type
2.8 V6
Transmission
Manual
2WD / 4WD
4WD
Thanks for the input, litleblue, I will try some of this out tonight.

I recovered from my self-disgust and reset the carb mixture screws to 3 turns. The truck started up pretty easily.

I posted a while back in another thread about some weird parts that had been partially removed from the truck: https://www.therangerstation.com/forums/index.php?threads/85-ranger-exhaust-part-identification.182618/

I tried covering up what I believe is the pipe that would be connected to a secondary air pump, and the truck sounded much better. I will work on coming up with a more permanent solution to seal this off, I was under the impression that it wasn't an issue, but on consultation with some older, more experienced friends, it sounds like I may be having issues due to lack of exhaust backpressure.

My older friend is also working on recovering a good condition ford pinto carb he gave to a friend who didn't end up using it, so I may have the opportunity to see if it's simply my carb in need of a rebuild.

Will update when things start happening!
 

litleblue

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Joined
Aug 16, 2007
Messages
31
Reaction score
4
Points
8
Location
Fairbanks Alaska
Vehicle Year
1984
Make / Model
Ford
Engine Type
2.8 V6
Engine Size
2.8
Transmission
Manual
2WD / 4WD
4WD
You are on the right track with the Pinto/Mustang II carb and duraspark ignition. The EECIV has to be all together working properly or or all gone there is no halfway.
Your other photos, the exhaust thermactor check valve is the part that was making noise. It should be hooked up to the air pump through a couple of valves. The valves are the air bypass and diverter. Air bypass dumps air pump air to atmosphere and the diverter valve chooses the path air goes to, exhaust manifold on warmup or center of cat when warm. This is all controlled by the computer.

The piece of tin on the right hand exhaust manifold is to keep the carb from icing. There is a hose that goes from the tin to the air cleaner and provides heated air for the carburetor. This is controlled by a vacuum actuated thermostat in the air cleaner and a mixing valve actuator on the inlet of the air cleaner. This system should be hooked up and operational when you convert the engine to a non feedback carb and duraspark.

The EECIV feedback system works well, however critical parts haven’t been available for over 15 years. Some of the parts are mixture control solenoid on the carb, knock sensor, solenoid valve assembly to operate the vacuum actuated valves. With these or any emission related parts broken the computer doesn’t know how to adjust the systems and simply goes into limp mode. When this happens the timing is set to 10 deg and won’t change, the mixture control solenoid is set to full rich, the engine runs poorly and gets about 10 to 13 mpg. Best thing to do is round up a non feedback carb and a centrifical/vacuum advance distributor and eliminate the EECVI system.
 

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