Ton of Fun

Hello, first post in this forum. I recently purchased this 1990 G30 1-ton cargo van. 5.7L V8, TH400. Once it warms up, it runs good, but if when started cold, it idles up and down and at slower speeds it seems to load up and bog. I sprayed some throttle body cleaner in the throat of the TBI unit (engine off), on the throttle plates and on the back of the throttle plates and that seemed to help. It's been very cold here in Vegas the past few days (upper 20's at night). It starts on the first try and I can easily keep her going by opening the throttle plates as needed for the first minute or two. After that she won't die, but runs a bit rough and rpm varies slightly up and down. Before using the throttle body cleaner, the idle varied up and down a lot. So, I've been trying to figure this out and I noticed that both injectors are dripping--no, dumping--fuel onto the throttle plates. If you look closely at the photo I've included, you can see the fine cone-shaped spray, but more noticeable is the almost solid stream of fuel dripping from the injector (both injectors are doing this). I've never owned a TBI before, so this all new to me. I plan on ordering a rebuild kit for the TBI. From what I've read, the most likely cause for a leaking injector is faulty O-rings. I was also considering ordering new injectors, but is there a chance these injectors are still good and the fuel I'm seeing is leaking past the O-rings? The injectors should never drip, correct? Do you think this is the most likely cause of the driveability problems I'm having? It runs good at higher rpm's....presumably the bigger volume of air being sucked in is compensating for the added fuel? Thanks for any help...

canucklehead

You could also pick up a couple used ones at a wrecker/salvage yard....

canucklehead

Also replace the fuel filter and do a fuel system clean....

Ton of Fun

Thanks for the response. I went ahead and replaced the injectors today and replaced the fuel pressure regulator diaphram as well. Now the spray pattern looks much better, a fine, cone-shaped spray. However, now she won"t idle. I had to give it some gas to start it and then keep it running using the accelerator pedal. I found an old, brittle, crumbling vacuum line going from the intake manifold the the round vacuum pot and replaced that but had the same condition. Then I unplugged the coolant temp sensor and with that unplugged, it will stay running on its own, though it idles up and down. I will replace the coolant temp sensor, fuel filter and clean out the IAC on my next day off. Any other ideas?

canucklehead

Air filter? Check for codes....