89 BII

[McWillies]

Ok, I got a problem with my 89. When I first start her up in the morning, acceleration is fine (not great but ok). Usually when I'm driving I go right onto the highway for 20 or so miles. I run around 65 the whole way, not very comfortably but if I go slower I'll get run over. When I get to my turn off the highway is when I realize that my acceleration has decreased greatly. The acceleration seems extremely slow, I can have the throttle wide open and it feels like I'm barely moving. I can really tell because the guy behind me always rides my ass because I'm going so slow. Also, when the engine is cold, it cranks up much faster. Within a second of turning the key it starts up. After it's warmed up, she takes a few seconds, nothing scary but longer than when cold. Went out the other day to try and pull some OBD1 codes, did the KOER method but I came up with no codes which seems weird. My check engine light isn't on but would it need to be to throw a code? Ever since I got this BII it's had trouble going 65 on the highway. Accelerates pretty slow even when cold, then when I get to a hill, I have to floor it to keep up. I believe that is what's causing my horrible gas mileage (10 or 11 mpg). Any thoughts are appreciated.

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[RayInStl]

My best guess is a large vacuum leak. Vacuum leak causes the truck to think it's lean so it adds fuel. Too much fuel = bad gas mileage and no power. But there's a million other things that can cause it too. Like worn rings, bad lifters, etc. Does she smoke?

 

[McWillies]

My best guess is a large vacuum leak. Vacuum leak causes the truck to think it's lean so it adds fuel. Too much fuel = bad gas mileage and no power. But there's a million other things that can cause it too. Like worn rings, bad lifters, etc. Does she smoke?

Not sure if I'm gonna sound stupid mentioning this now or if it's a big deal but my filler neck has a crack in it. When I fill the tank up all the way, some gas pours out near where the filler neck would be. I never fill up to avoid leaving gas in the middle of a gas station. I never notice smoke coming out of the exhaust, but the other day when I was warming her up and revving a little for the self diag test, I noticed some smoke coming from somewhere. I had the hood up so I couldn't see anything. I'm not sure what a vacuum leak would sound like but my engine sounds healthy. Where might a vacuum leak come from?

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[McWillies]

My best guess is a large vacuum leak. Vacuum leak causes the truck to think it's lean so it adds fuel. Too much fuel = bad gas mileage and no power. But there's a million other things that can cause it too. Like worn rings, bad lifters, etc. Does she smoke?

Been anticipating your answer the last 2 days lol. Went and looked under the hood and at the vacuum hose diagram. I checked all the ones I could find for wear and tear but they all seemed to be in good condition. Read somewhere that a fuel pressure regulator could cause the engine to run rich. Do you know where I could find the FPR?

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[JerryC]

The worst vacuum leak I have had was the upper intake gasket. It felt like it had about 40HP. One place most wont notice is the vacuum booster or the grommet at the booster. Look up how to use propane to find a vacuum leak, if that gives you the willies check out using a smoke generator.

Your highway issue sounds to me like a clogging fuel filter or possibly a dying TFI module. The hot start issue sounds like a TFI issue.

I've seen filler necks on sale for 89-90's in the past, you might be able to get a new one.

 

[McWillies]

The worst vacuum leak I have had was the upper intake gasket. It felt like it had about 40HP. One place most wont notice is the vacuum booster or the grommet at the booster. Look up how to use propane to find a vacuum leak, if that gives you the willies check out using a smoke generator.

Your highway issue sounds to me like a clogging fuel filter or possibly a dying TFI module. The hot start issue sounds like a TFI issue.

I've seen filler necks on sale for 89-90's in the past, you might be able to get a new one.

"if that gives you the willies" that made me lol. Where might I find the tfi module on my BII?
By vacuum booster do you mean brake booster? I checked that and the hose looked good, not sure about a grommet.
I found this, not sure what it is or if it's what you are talking about.

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[RayInStl]

The way I check for vacuum leaks is to spray around the vacuum hoses and the base of the intake with staring fluid. If you have a leak, the engine will rev for a second when you spray the leak. Keep the spray away from sparks or electronics. It is flammable, after all.

Another possible suspect is a plugged up catalytic converter. A plugged cat will cause the engine to struggle to exhale it's exhaust. They will run like a dog if the cat is clogged. I don't know a good test for this other than driving a bunch at night and seeing if your exhaust manifolds are glowing cherry red. lol. I don't think an 89 would have the second oxygen sensor after the cat to trigger a check engine light for that.

 

[RayInStl]

Which motor is in that?

*EDIT* nevermind, I'm dunce. I see it's the 2.9L.

The fuel pressure regulator is on the driver side of the motor next to the intake and at the back of the motor. It's cylindrical and metal. It has a vacuum line coming off of it and hooks to the fuel rail. If you need a pic, I can take a pic of mine when I'm home from work. A good sign that a Fuel Pressure Regulator is bad is to take the vacuum line off and look for gas. If it has gas in the vacuum line, the rubber diaphragm is toast and not working. I don't know if these have a schrader valve on the fuel rail or not, but if they do, you can use a fuel pressure tester from autozone (rent it) and see if you're getting good fuel pressure.

 

[McWillies]

The way I check for vacuum leaks is to spray around the vacuum hoses and the base of the intake with staring fluid. If you have a leak, the engine will rev for a second when you spray the leak. Keep the spray away from sparks or electronics. It is flammable, after all.

Another possible suspect is a plugged up catalytic converter. A plugged cat will cause the engine to struggle to exhale it's exhaust. They will run like a dog if the cat is clogged. I don't know a good test for this other than driving a bunch at night and seeing if your exhaust manifolds are glowing cherry red. lol. I don't think an 89 would have the second oxygen sensor after the cat to trigger a check engine light for that.

Been reading a lot on the ways to check for vacuum leaks, haven't seen that one yet though. Are there any "house-hold" items I could use to test for leaks?
Never really thought about the cat being plugged up, driving all night isn't really an option lol. If the cat was plugged would I experience any overheating? I wish I could see my RPMs when idling and running but my tach doesn't work.

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[RayInStl]

Been reading a lot on the ways to check for vacuum leaks, haven't seen that one yet though. Are there any "house-hold" items I could use to test for leaks?
Never really thought about the cat being plugged up, driving all night isn't really an option lol. If the cat was plugged would I experience any overheating? I wish I could see my RPMs when idling and running but my tach doesn't work.

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Has it been overheating? Cause that's not good. These motors are known to crack heads when they overheat. On a properly running motor, I wouldn't expect clogged cats to cause it to overheat. It may run hotter, though, since exhaust gases (and their heat) are not being properly vacated.

 

[McWillies]

Has it been overheating? Cause that's not good. These motors are known to crack heads when they overheat. On a properly running motor, I wouldn't expect clogged cats to cause it to overheat. It may run hotter, though, since exhaust gases (and their heat) are not being properly vacated.

No no no, it hasn't been overheating haha. That's why I asked, because it doesn't overheat. Is there any other way to test for a clogged cat besides running around in the middle of the night?

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[RayInStl]

There's a few ways to test them. If you have an infrared thermometer, you can read the temperature of the exhaust pipe in front of the cat and behind it. If it's working, the exhaust leaving the cat should be hotter that the exhaust coming in. If the cat is plugged up, the exhaust leaving the cat will be significantly cooler than the exhaust coming in.

A second method is to use a vacuum gauge hooked to the intake manifold. Start the engine and note the vacuum at idle. Then blip the throttle a couple times. When the engine revs, the vacuum should drop. As soon as the revs come down, the vacuum should go back to where it was. If it takes a while to come back up, your exhaust is plugged. Another vacuum check is to check the vacuum at idle, then rev the engine to 2500 RPM. The vacuum will drop, but should come back up pretty close to what it was at idle. If it's more than 10% lower or continues to drop, then it's clogged.

That second method was gotten from https://www.2carpros.com/articles/how-to-test-a-catalytic-converter. I knew the first method, though they cover that, too.

The last method is the most reliable and involves a tool called a backpressure gauge. You can buy them at autoparts places, and you may be able to rent them. You'd have to call autozone or your preferred auto parts house to check. To use the gauge, remove the oxygen sensor that's before the catalytic converter and hook the gauge up in it's place. Start the truck and read the gauge. It should be very low. Less than 2psi at 2500 rpms. Near 0 at idle. If it's high, then your cat is clogged.

 

[McWillies]

There's a few ways to test them. If you have an infrared thermometer, you can read the temperature of the exhaust pipe in front of the cat and behind it. If it's working, the exhaust leaving the cat should be hotter that the exhaust coming in. If the cat is plugged up, the exhaust leaving the cat will be significantly cooler than the exhaust coming in.

A second method is to use a vacuum gauge hooked to the intake manifold. Start the engine and note the vacuum at idle. Then blip the throttle a couple times. When the engine revs, the vacuum should drop. As soon as the revs come down, the vacuum should go back to where it was. If it takes a while to come back up, your exhaust is plugged. Another vacuum check is to check the vacuum at idle, then rev the engine to 2500 RPM. The vacuum will drop, but should come back up pretty close to what it was at idle. If it's more than 10% lower or continues to drop, then it's clogged.

That second method was gotten from https://www.2carpros.com/articles/how-to-test-a-catalytic-converter. I knew the first method, though they cover that, too.

The last method is the most reliable and involves a tool called a backpressure gauge. You can buy them at autoparts places, and you may be able to rent them. You'd have to call autozone or your preferred auto parts house to check. To use the gauge, remove the oxygen sensor that's before the catalytic converter and hook the gauge up in it's place. Start the truck and read the gauge. It should be very low. Less than 2psi at 2500 rpms. Near 0 at idle. If it's high, then your cat is clogged.

Ok, thanks a lot. Too late to do anything today, but I'll try tomorrow.

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[RayInStl]

I should note that there are LOTS of things that can make a car lose power. All of the below are just off of the top of my head:

• Faulty fuel pump
• Clogged catalytic converter
• Faulty fuel pressure regulator
• Faulty or dirty fuel injectors
• Engine timing off
• Excessively worn piston rings

Does the engine run well? Does it sputter, surge, or otherwise run "rough"? Do you smell gas? Are there any other symptoms other than just loss of power?

 

[McWillies]

I should note that there are LOTS of things that can make a car lose power. All of the below are just off of the top of my head:

• Faulty fuel pump
• Clogged catalytic converter
• Faulty fuel pressure regulator
• Faulty or dirty fuel injectors
• Engine timing off
• Excessively worn piston rings

Does the engine run well? Does it sputter, surge, or otherwise run "rough"? Do you smell gas? Are there any other symptoms other than just loss of power?

The engine seems to run great. No sputtering or surging. The engine does have some vibration in the engine bay while idling, but it's not excessive. The only time I smell gas is when I fill the tank too much and it spills out of the crack in the filler neck. No other sypmtoms really. Just slow, but smooth, acceleration. And no power when going uphill. The responsiveness of the engine when pushing the gas pedal seems ok, not really sure what "good" would be. One thing I've noticed is the sound of the engine. I'm not sure if it has some kind of aftermarket exhaust (covered in surface rust) but it's fairly loud. Possibly an exhaust leak somewhere.

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