Just bought a nice 1988 T/A. It is a 5.0 TPI auto trans with the T-Top. It is really clean, and has been pretty well taken care of but has a rough running issue.
I believe after doing some research, thinking, and diagnosis that it has a couple, or a few plugged fuel injectors because it runs smoothly upon cold start. (as I understand it) on the 88 models there is a supplemental enrichment injector in the upper plenum and upon (cold) startup all 8 cyls are pulling air and (extra) fuel from the plenum?.?..but, in my case, as soon as the enrichment circuit turns off, the (9th) injector is closed, and each cyl begins to only get fuel from its own injector, it begins to run roughly. #1 and #4 cyls show no change when the plug wires are pulled from the cap one at a time, and the plugs are firing. The car has new cap, rotor, wires, plugs etc. and they are installed correctly (18436572, clockwise on the cap-and all connected to the correct plugs) so I am 99% sure that it isn't an ignition problem, and if it were a stuck or burned valve, the motor would be running rough at ALL times.

I have read that the yellow top bosch type II 19lb/hr (ford) injectors are a direct, and much better, and more reliable replacement for the stock injectors that the car came with. AND.....I happen to have a set with only ~ 8k miles on them lying around in the boxes that I have been holding onto in case I ever needed them. (yes they came out of a mustang, and yes, I still have one of those too...sorry)
Are these a direct replacement? (save for the shorter o-ring to o-ring distance?) Will they work correctly with the stock fp regulator? Would it be ok to keep the stock "enrichment" / 9th injector while replacing the other eight with the new type injectors since I only have eight of them? If so, I will install them and hopefully it will solve this issue.
I hope that I can learn a lot about these cars from everyone here and maybe even help some of you at some point...I am 44 now and this is the first GM F body I have ever owned so I am mostly un-familiar with the particulars of working on one of them. I have always thought they were good looking cars, and I bought this one because it was too nice to pass up for the amount of $$$ I paid to obtain it.

Thanks,
John C.

 

Hey John.. any injector is better than the stock injectors. LOL
The gen ll bosch yellow tops are a decent injector. The bosch lll's are the next generation after the yellow tops... great product. The yellow tops will fit. When you install them you can use the clips, or if they are too short just add another oring to the bottom of the injector either way it will be fine. If you decide to go with the double orings install them into the intake manifold first and make sure to lubricate the upper orings before installing them into the rail. If we can help you in any way please do not hesitate to contact us.

www.southbayfuelinjectors.com
516-492-6504

 

Thanks. Hey you guys advertise the little "adapters" that are used to relocate the lower o ring @ the proper distance from the top o ring in this (tpi) application? Do you sell those things by themselves, or would someone have to buy the injectors with them on there already? It says GenIII, will they work on GenII injectors?

Also, if I use these bosch II's on this motor, will I have to make any adjustment to pressure, or just throw them in there and run 'em as if I were replacing with original stock-type ones? What lb/hr rating are the originals? Aren't they 19Lb/hr on the 1988 5.0 TPI? Do I need to replace the #9 injector in the plenum too, or can I keep the original one in there if it is working?

 

Yes we are. We worked on those adapters for a long time before we were satisfied with the design and the fit. We were thinking about making them for the gen ll's but it did not pay since most people prefer the bosch lll's. Unfortunately we need to apply the adapters, they need to be applied properly, we have a tool that enables us to do that, because if they aren't applied correctly you will definitley have a vacuum leak. You do not have to purchase injectors, if you have a set of bosch lll's we will be more than happy to apply them to your injectors.
As far as the yellow tops are concerned you will not have to make any adjustments to the pressure, and yes 19lb is the way to go. Pressure should be around 43.5psi. If the #9 injector is working then there is no need to replace it.

 

Thanks. I figured the adapters would not fit GenII's, but as long as they (genII's) will work without adapters, that's all that I care about. I'm going to use them 'cause they're almost new, (mileage-wise) and I already had them lying around. I took them out of my 2000 4.6L Mustang GT back in 2001 when I installed the Vortech SQ kit because It came with a new set of (larger) injectors.
Just out of curiosity, why do most people want te GenIII's. Are they that much better than the II's, or is it just because they are the "newer" design? Would it be worth the $ for me to buy those instead? The car is stock, and exhaust is probably the only thing that I will be changing for a while so I think that what I already have will be fine, but, I am not as familiar as you with this particular subject.
Thanks very much for all the info, I appreciate you taking the time to help me out.
John C.

 

If you already have a set of injectors and they are in good condition there is no reason why you need to spend more money. Besides, they are bosch,, you should be just fine. Regarding the injectors...both are made by bosch, both have a 4 spray pattern which gives more efficient atomization of the fuel, the bosch lll's are a newer design and an upgrade over the gen ll's.

 

Hey, Figured this would be a good thread to follow...

 

Cool, now all I have to do is find time to do the swap-out. Gotta work 12 hr days for the next 10 days straight...Today, I was off but Tropical Storm Hermine messed that up-it's been raining here all day and I have to work on the car outside 'cause my garage has too much (of my wifes) crap in it to put another car in there.
John C.

 

Allright, I finally got time to work on the T/A and I am at a point where I need some answers now....

A: Do I need to remove the upper plenum AND the intake runners in order to get the fuel rails and old injectors out? I have removed the upper so far, but not the runners.

B:Also do you just disconnect the fuel lines at the front, and remove the rails and regulator all as one unit, or do you have to dis-assemble the right and left sides from each other to get them off? One more thing..

C:This car has a fitting @ the rear of the rail on the left side that connects the fuel line for the 9th injector and I've loosened the fitting, but the end of the line won't come out of the back of the fuel rail. Can someone tell me what I might need to do to get this thing the rest of he way apart?

I've no experience with these TPI motors, so I'm just guessing at how to do this job right now and it's a P.I.T.A so far! Also, I'm Sorry if this is not the right section for this to be posted in (now that it pertains to actual engine work...)
Thanks in advance,
John C.