Fuel Injector Help Please

[codewize]

89' STS 2 port TBI - RECENT HISTORY: Replaced fuel tank, pump and sending unit. All were used but from a desert car so there was no rust. The inside of the tank was professionally cleaned before installation. The tank is spotless inside and out.

After replacement, the car ran fine for 3 or 4 days and a couple tanks of gas. All of a sudden the car was starving for gas. My initial thought was that the new pump had a little extra pressure and blew something loose from the line or filter. I looked close at the injectors and one of them wasn't firing at all. Just dripping gas. I play around for a few minutes with it and it started working.

Today the car is at the point were when this thing will run fine then when it starts to go south it dies within a few seconds. I can get out and tap the injector and it comes right back to life. This cycle repeats itself about ever 4 or 5 miles.

QUESTIONS: Can this be a bad injector. If so, what brand should I buy? If you think it's something else, what? The fuel filter will be replaced tomorrow.

 

[DaveSmed]

I'd feel pretty secure in saying its the injector. Did you measure the injectors resistance by any chance? Disconnect the connector, and ohm it out. When it's acting up, it will probably show infinity, or open.

 

[codewize]

Good call. Thanks. Funny thing is now, I smacked it a couple times last night and it's seems to be running fine. we'll see today after I do the brakes

I'd feel pretty secure in saying its the injector. Did you measure the injectors resistance by any chance? Disconnect the connector, and ohm it out. When it's acting up, it will probably show infinity, or open.

 

[codewize]

Today's update

Ok. Brakes are done and I've come to the conclusion that my car sucks. The fuel injector is back to it's thing. However, both times it died today I got out, armed with my digital multi meter, took the air cleaner off and bam 1.40 ohms. So I scratch my head expecting to see 0 or OL. I plug it back in and the damn thing is working. Twice that happened. I guess I have to wait until it 'really' dies?

So anyway does anyone recommend one type / brand of injector over another? Bosch?

 

[codewize]

It now seems that when I put the ohm meter on the injector, it must ground it out or something, because when I measure resistance it's correct and then the injector works.

 

[Katshot]

Check the connector on the injector. They have been known to act up. You can also swap them (the connectors) and see if the problem moves the other injector to verify whether it's the injector or not. If you swap the connectors and the problem doesn't move, the injector's bad. Hate to say it but in that case, I'd replace both. My guess is that something from the work done affected the injector in some way.

 

[codewize]

Funny thing. Later last night without changing anything the other injector was acting up. I then went back to thinking it's a fuel pressure problem. Today I put some gas in the tank and the car is running great. I almost think that the problem only occurs when the fuel is low, 3 gals or so.

If it's a pressure problem, why does just tapping the failing injector resolve the issue. If it's a clogging problem why was it consistently only one injector until late last night? And if it's a bad injector why is the car running fine now with a half tank of fuel. I guess we'll see tomorrow when I run the fuel down a bit. I'm trying to lay my hands on a pressure gauge.

Now we need a little more on the history. Prior to changing the fuel tank, when it got down to 4 or 5 gals the car would start acting like I was out of gas. The lower it got the worse the symptoms got. I assumed at that point that because I knew I had a leak that air was getting sucked into the fuel system. I was happy to see these symptoms eliminated for the first 3 days with my new tank.

 

[CaptainZilog]

I'd put some methanol in your tank just in case you have water in there, then I'd get ready to replace the fuel pump.

 

[Katshot]

Each injector will react slightly different in that type of situation and don't totally discount the possibility that your tapping was also reaching the fuel pressure regulator built into the TBI unit. Hard to tell without some hard data from a pressure gauge.

 

[codewize]

UPDATE: down to 3 gals and no sign of brokeness. I don't get it. Maybe there was something up in there and it finally came out?

CaptainZilog, thats been done. We put in 2 bottles the day we put the tank in and I've put 2 more in over the last week. I really hope it's not the pump

Katshot, I'm trying to get my hands on a guage without buying one. I wondered about the regulator myself. I'm sure when I show up in Carlisle there will be something exciting happening with this car. LOL