It is not an acurate test but has worked for me so far. Take the fuel line off of the back of the fuel rail and run it to a glass jar. It should take a 1 to 1 1/2 minutes to fill or so. It will fill it quick with fuel. I dont have any prssure gauges and not ever really used them so this is how I go about it.

Do you live in a humid area? In my area it is humid and from my way of thinking it casuses havoc on our fuel systems. You may have a dirty fuel system. In each truck I have worked on in the past, all but one had great fuel flow. Starting at the tank, it may have rust build up in it. I clean my tanks with white vinegar, the rust looks bad in them but when you let it soak a few days with vinegar, you will see there is no damage from rust. I think it is a build up of additives from the gas in the tank. It definitely looks like rust. A 1/4 inch build up is not unusual. Do NOT use the drain bolt to empty the tank. It will strip out the threads from the build up on the threads. I learned that the hard way. ( TWICE, I am a slow learner,lol)

The Fuel pumps I use I get from ebay for about $30. Make sure you get an entire pump assembly with the fuel filter on the end of the pump and a rubber disc that holds the pump into the bracket. Also the "J" line is most likely going to be clogged on it as well which is the Return line to the tank. Be careful when trying to get the Fuel Pump Assembly out. Sometimes it will like to rust to the rubber line that is attached to the frame. It is a hard and expensive part to find. Be careful with the metal line on top of the fuel pump holder. You dont say if you have a Runner or Pickup. Pickups are worse as the tank is usually more covered in mud and will rust the top out.

Usually the Return line on the frame from the motor to the tank is going to be clogged. I soak it with Marvel Mystery Oil or PB Blaster for a few days and using low pressure air, I blow the line out. Soak for a few days so as not to compress the clog. (I do the same for brake and clutch lines.)

The Fuel Rail can have some nasty build up in it as well. I take it out and clean with carb or injected fuel can cleaner in the spray can. I have gotten flakes out the size of my finger nail. Nastyyy!!!

85-87 have a poorly designed Injector Connector. I get mine from www.connectorfast.com Alex there is a great guy to deal with and knows his stuff at 208-288-0320.

On each build I have done, I have tried to show how bad the fuel system gets. On my 88 Runner build below in the link on the first page, I have some more info listed that can help show some things I have mentioned.

The LED basically shows that the computer is sending the signal and if I recall right it is about 10 flashes per second. Doesnt necessarilly mean that enough power is getting to the injector, but if your wiring is good, I would start looking at the fuel system.

To do the fuel system, I consider it about a $80 fix. $25 for Red Kote, $30 for a fuel pump, and the rest for vinegar and a rust dissolver for the lines. The ebay link for the fuel pump is no longer available in my 88 Runner build but there are others available. I have used several of these pumps on different trucks and not one has failed yet. Just make sure you keep your fuel tank above 1/8th tank. I prefer 1/4 tank to keep the pump cool.

You have already taken care of your injectors. When you pull the fuel rail out, check to see if the screens in your injectors are clean. I can post a way of cleaning them at a later time if you need to clean and check them. It is on the later half of my 86 Runner build using a 9 volt battery if you need that information sooner.

 

Since this thread came up for me when I was looking at noid procedure I figured I would add that note here as well. After disassembling the plenum I wasn't getting any injector pulse until I slipped the ground wire back over the bolt between cylinder 3 and 4. Ground in question is here

 

Good catch on that. That is the ground and it will need to be grounded when running the test. I will mention that on the first post so some one wont have that problem. Thanks for the post.

 

Today I was helping a friend work on a 93 pickup with 423,000 miles on it and it has a miss on #4 cylinder. We are getting fire to spark plug and now know it is on the fuel injector side. The injectors were recently tested and cleaned so we know it is not getting a pulse from the computer to fire the injector.

We did not have an LED to test the injectors connector but did have the 194 bulb. When connecting the bulb to one of the known good injectors, the bulb stayed lit solidly and bright. I am guessing the filament can not dim fast enough to show pulses. On an LED I get about 10 flashes per second. My guess again is the LED can react quicker to electric pulses then what a bulb can do.

When connected to the known bad injector it would be dim at times or not light at all. I am suspecting we have a bad wire or crimp that is needing repaired.

Just wanted to mention this as we were to far away to go get a LED and used a bulb for testing. Some tools just cant be found or you have to come up with a way to test things that are not conventional.

 

Great idea