3500 Swap - '99 GA Which fuel injectors to use?

[Starglow]

Hi.... as some of you know, I'm doing a 3500 swap on my '99 GA. I need some recommendations on which fuel injectors to run with the 3500. Since I have a '99, the stock fuel injectors are 19# Multec 1.

Will the 3500 run fine with that setup using the stock 3400 fuel rail or is it really worth the trouble of splicing in the Multec 2 FI harness connectors to upgrade to 28# Multec 2 injectors and a 55 PSI FPR?

I will not be doing a tune right now and will be using the 52mm throttle body on the stock 3500 UIM. Later on I will upgrade to a 65mm throttle body and possibly a PCM update when more funds are available. If I install the 28# injectors now, then I won't have to pull the UIM when I do the TB & PCM upgrades later.

FYI...I'm working on a plan to adapt LX9 headers into the GA with the crossover pipe running underneath the car like a G6 instead of behind the engine/trans. Haven't worked out all the details yet, but it looks promising so far.

Thanks.....!

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[Realestdriver]

You can just use the 19# injectors for now, unless you plan on doing a lot of WOT pulls (injector duty will be around 97%). The 3500 will run fine with these injectors, this is my current setup on my '99 minus the 3500 UIM. I would however recommend the upgraded injectors and high FPR, once you are ready for a tune.

[Realestdriver]

. . . . .28# is the way to go btw

[Superdave]

19's at 43.5 PSI are a stretch for a 3500, realestdriver is correct. you will run it lean with a stock tune at WOT. You could get away with just swapping on the 55PSI FPR and make up for that a little but it's still not right.


The OBD1 tunes I sell for the 3500 are set up for the stock 3400 M2 injectors and the 55 PSI FPR, for a bone stock 3500 that works out great. The only one that i pushed the injectors close to 80% on was one with a P&P'd top end and 10.8:1 scr.


If you do change injectors, pay close attention to the spray patterns. You want something narrow like the stock M2's.

[Starglow]

19's at 43.5 PSI are a stretch for a 3500, realestdriver is correct. you will run it lean with a stock tune at WOT. You could get away with just swapping on the 55PSI FPR and make up for that a little but it's still not right.


The OBD1 tunes I sell for the 3500 are set up for the stock 3400 M2 injectors and the 55 PSI FPR, for a bone stock 3500 that works out great. The only one that i pushed the injectors close to 80% on was one with a P&P'd top end and 10.8:1 scr.


If you do change injectors, pay close attention to the spray patterns. You want something narrow like the stock M2's.

I found this on a Grand AM website:

for injectors not requiring you to cut or splice your harness in any way are the following
95 Bonneville super charged 28lbs
94-96 caprice these are 24lbs

Do you concur with this and/or know of a good place to source the '95 Bonneville injectors from?

Here is the thread link for reference although it is for a 3500 top swap:

http://www.gaownersclub.com/forum/sh...d.php?t=130053

Thanks....!

[Superdave]

You can use 3.4 DOHC injectors as well, they are Multec 1 and will swap right out with yours. They are about 24lb/hr @ 43 PSI. I have used them in 3400's and 3500's however the spray pattern is not ideal. It's very wide and almost looks like a fogger. Probably a good choice if the engine was going to spend most of it's life on the highway though.


Since you don't want to change around the harness (which is really quite easy) I'd just put the 55 PSI FPR on your fuel rail. That will bring your 19lb/hr injectors up to 22lb/hr and you'll have enough fuel for the 3500. Make sure to get it tuned though.

[slowalero]

Probably doesn't help much, but here's an up close shot of the 28's. Here you can at least see the harness connector is identical to the 3400. This works for you, like everyone else said. And for the other reasons too, I got 'em for insurance. Who here never hits WOT?
IMG_4629.JPG

[Starglow]

Probably doesn't help much, but here's an up close shot of the 28's. Here you can at least see the harness connector is identical to the 3400. This works for you, like everyone else said. And for the other reasons too, I got 'em for insurance. Who here never hits WOT?
IMG_4629.JPG

Where did you buy those from if you don't mind me asking?

Thanks...!

[boomofdoom88]

No hes got a 99 which has different connectors. But IF you wanna change your fuel injector harness....

http://www.ebay.com/itm/380380799400...84.m1438.l2649

28lb injectors on ebay. Not a bad price either. I got a complete new set of injectors this way for $19.99 plus shipping cuz the guy didn't know what he had.

[Starglow]

No hes got a 99 which has different connectors. But IF you wanna change your fuel injector harness....

http://www.ebay.com/itm/380380799400...84.m1438.l2649

28lb injectors on ebay. Not a bad price either. I got a complete new set of injectors this way for $19.99 plus shipping cuz the guy didn't know what he had.

Thanks....!