Engine feels like it is only running on three cylinders

Hi,

The first thing to do is check for diagnostic trouble codes. This truck has an OBD1 system that doesn't require a scanner to retrieve codes. Here is a link that explains how it's done:

https://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995

Next, oftentimes rough running conditions can be attributed to an engine vacuum leak. If you haven't yet, check for leaks. Here is a link explaining how that is done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know what you find. Also, considering the mileage, we may need to perform a compression test to make sure one or more of the cylinders are weak.

Regardless, let me know what you find.

Take care,

Joe

Hi,

When you check for vacuum leaks, try using carburetor cleaner. It won't bubble because there will be a vacuum inward. If there is a leak, the carb cleaner will cause the engine RPMs to increase.

If you want to test compression, it isn't hard to do. You will need a compression gauge, but most parts stores will lend one to you. Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-test-engine-compression

Let me know if you are comfortable trying that. Also, if you have questions on the vacuum concern, let me know.

Take care,

Joe

Hi,

The compression sounds excellent, so we know it has a healthy engine.

It could be a fuel injector issue. However, I still feel it would have set a code.

What you could do is a fuel pressure test and then see if the pressure drops off fast. If it does, that could indicate a leaking injector. Here is a link that shows in general how to test fuel pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Your vehicle, because of the model year, will require a T fitting between the injectors and the supply. At that T is where the gauge is placed.

I do have another question. Are there any odd sounds from the exhaust that may indicate a possible partially plugged catalytic converter?

Take a look through this link. You may find it of interest.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know. Also, let me know if this has the 22R or 22RE engine. I'm assuming it's the 22RE. Additionally, let me know if you smell fuel, see smoke from the exhaust, or anything you feel may help me. If you could record it running and upload it for me to hear, it may be helpful.

I attached the fuel pressure specifications below for the 22RE engine. If you have the 22R, it will have a mechanical fuel pump and the pressure is much lower, so let me know.

Take care,

Joe

See pic below.

Did you ever try to retrieve codes? If we could narrow it down to a specific cylinder, then we could focus on it.

Here is a link you may find helpful if checking the injectors:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Let me know.

Joe

Hi,

Was the spark plug wet? Did you check to confirm if it is getting spark? Here is a link that shows how it's checked:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Let me know.

Take care,

Joe

Hi,

Yes and no. If you are getting the timing light to strobe, that indicates power is being sent. The spark plug can fail. The reason I asked if it was wet was to see if there was a possible injector issue or fuel pressure issue. Now, if it is dry and the spark plug has spark, it could indicate the injector isn't injecting fuel.

Let me know.

Joe

Hi,

Thank you for the update. I'm glad to hear it's fixed.

Please feel free to come back anytime in the future if you have questions. You are always welcome here.

Take care,

Joe