Replace injectors as Maintenance?
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,964
Likes: 242
Replace injectors as Maintenance?
94 LT1 ~115k
Would you ever replace your injectors as maintenance on an otherwise fine running motor? My 94 runs just fun, idles smoothly, and the motor doesn't need a thing. But, it's nearly 24 years old and has 115k miles. It sees about 5-6 tanks of fuel over a summer. The injectors, fuel pressure regulator, and fuel pump are all original. I've had the injectors out while doing other work and they did receive new o-rings.
I'm considering replacing all of it for no other reason than they are at/beyond the service life I'd expect and I want to get in front of any issues. I'm just not sold on the whole idea yet because part of my says don't fix what isn't broken.
What do you think?
on the menu:
injectors (professional rebuild or new replacement)
fuel pressure regulator
fuel pump (filter too, but that's been replaced before)
Would you ever replace your injectors as maintenance on an otherwise fine running motor? My 94 runs just fun, idles smoothly, and the motor doesn't need a thing. But, it's nearly 24 years old and has 115k miles. It sees about 5-6 tanks of fuel over a summer. The injectors, fuel pressure regulator, and fuel pump are all original. I've had the injectors out while doing other work and they did receive new o-rings.
I'm considering replacing all of it for no other reason than they are at/beyond the service life I'd expect and I want to get in front of any issues. I'm just not sold on the whole idea yet because part of my says don't fix what isn't broken.
What do you think?
on the menu:
injectors (professional rebuild or new replacement)
fuel pressure regulator
fuel pump (filter too, but that's been replaced before)
Melting Slicks
Joined: Jan 2014
Posts: 2,478
Likes: 254
From: Downers Grove Illinois
At a minimum measure the resistance of the injectors. On my 92 with 43 K miles I had 1 injector at 3 ohms, which is very low. I replaced all 8 with rebuilt Bosch III injectors and it was pretty easy.
Team Owner
Joined: Jul 2004
Posts: 28,353
Likes: 3,253
From: Hartford WI
IDK about your area but in my area, the fuel does have build up. I have verified them at a local tech college before and after cleaning. It lasts about 3 to 4 years, before the build up comes back so I send them out and while the intake is off, clean the TB and other misc stuff.
The fuel sitting in the injector could leave deposits or so my theory goes. Regardless, when I send them off, it reads say 250cc and when it comes back, it reads say 300cc so I know that 50cc is the loss.
In your case, it is easy to find stock sized injectors so I'd just buy a set of reman from FIC and get it installed same day. As I understand it, LT1 injectors are easier to do than L98. The reman price is the same as a set of used ones so why even bother to send them there and back? Just buy a set and toss what you have. They are probably the upgraded design.
https://fuelinjectorconnection.com/c...3-injector-set
The fuel sitting in the injector could leave deposits or so my theory goes. Regardless, when I send them off, it reads say 250cc and when it comes back, it reads say 300cc so I know that 50cc is the loss.
In your case, it is easy to find stock sized injectors so I'd just buy a set of reman from FIC and get it installed same day. As I understand it, LT1 injectors are easier to do than L98. The reman price is the same as a set of used ones so why even bother to send them there and back? Just buy a set and toss what you have. They are probably the upgraded design.
https://fuelinjectorconnection.com/c...3-injector-set
Race Director
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Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,964
Likes: 242
Thanks for the replies. I will ohm them - what is good, think I've read 12-14 ohms? The injectors are very easy to remove on an LT1 if it comes to it. How much hp can the stock injectors support? Car has ported heads, bigger valves and RRs, but stock cam which I someday plan to remedy.
I'm actually more concerned about the pump and FPR. Both are fine at the moment but given its age I worry the pump may leave me walking someday. I know a failed regulator can cause fuel to be drawn in the vacuum line.
I'm actually more concerned about the pump and FPR. Both are fine at the moment but given its age I worry the pump may leave me walking someday. I know a failed regulator can cause fuel to be drawn in the vacuum line.
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,072
From: Lansing MI
I agree about the pump. I wouldn't worry about the injectors until the first one fails, then replace them all.
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Team Owner
Joined: Jul 2004
Posts: 28,353
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From: Hartford WI
Thanks for the replies. I will ohm them - what is good, think I've read 12-14 ohms? The injectors are very easy to remove on an LT1 if it comes to it. How much hp can the stock injectors support? Car has ported heads, bigger valves and RRs, but stock cam which I someday plan to remedy.
I'm actually more concerned about the pump and FPR. Both are fine at the moment but given its age I worry the pump may leave me walking someday. I know a failed regulator can cause fuel to be drawn in the vacuum line.
I'm actually more concerned about the pump and FPR. Both are fine at the moment but given its age I worry the pump may leave me walking someday. I know a failed regulator can cause fuel to be drawn in the vacuum line.
Possible but if anything, I'd be more worried about the pulsator than the pump. If you are doing the fuel pressure regulator, might as well do injectors.
Racer
Joined: Apr 2016
Posts: 335
Likes: 93
From: San Antonio TX
The problem with that is that the first one that fails could immobilize the car. If it shorts out (a common failure mode), it will kill all four injectors on that side and the engine will die. Then you are looking at a tow (or in my case, two tows...).
Team Owner
Joined: Jul 2004
Posts: 28,353
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From: Hartford WI
Multecs don't like ethanol and most gas has some
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,072
From: Lansing MI
Lots of failures can result in towing your car. Proactive maintenance is not about what happens if you breakdown, its about what's most likely to breakdown. The fuel pump has a much higher probability of failure than any of the injectors or the regulator of any other part of the fuel system.
Melting Slicks
Joined: Jan 2014
Posts: 2,478
Likes: 254
From: Downers Grove Illinois
To what end? If it is running good, as your limited perception indicates, all the ohm readings tell you is the coils are in spec. You already know that. All it does is give you a false sense of security. Doesn't report the spray pattern and volume of the injectors. I guarantee there is some build up.
Possible but if anything, I'd be more worried about the pulsator than the pump. If you are doing the fuel pressure regulator, might as well do injectors.
Possible but if anything, I'd be more worried about the pulsator than the pump. If you are doing the fuel pressure regulator, might as well do injectors.
Last edited by JimLentz; Nov 6, 2017 at 10:54 AM.
Team Owner
Joined: Jul 2004
Posts: 28,353
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From: Hartford WI
I'd replace them with remans every few years just because of the build up that changes the flow rate and spray pattern and it is about as expensive to clean and test as to get ones that already are cleaned and tested. I have tested them and they have been found wanting after a few years. Coils were good it's just that the volume was uneven and all were lower than spec.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
FWIW, a low resistance injector likely means less fuel to that cylinder. As result, one of my intake valves was burned, presumably due to excessive lean condition in that cylinder.
So, "low resistance" is a sign of deterioration of the internal actuator coil of the injector. Definately want to correct that - and may I suggest replacing them ALL with alcohol immune injectors. Just a thought!
Last edited by Paul Workman; Nov 6, 2017 at 11:46 AM.
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,964
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Good discussion. The ohm test is just for an idea if the coil is good or not. Frankly, I want to replace most of the fuel system but to spread the cost I'll probably do it in pieces with the most likely candidates for failure first (pump).
I believe there are 2 Walbro pumps for our application. One of which requires heavier gauge wire. Would like a more plug and play option. Which is the lesser walbro that uses stock wiring? Will it support 400-450 flywheel hp? I'm hoping for that someday.
Can someone explain the pulsator? Is it in tank? Part of pump? If so, do aftermarket pumps include it? I've read that it serves little purpose other than to quiet down the pump a bit, is that true?
I believe there are 2 Walbro pumps for our application. One of which requires heavier gauge wire. Would like a more plug and play option. Which is the lesser walbro that uses stock wiring? Will it support 400-450 flywheel hp? I'm hoping for that someday.
Can someone explain the pulsator? Is it in tank? Part of pump? If so, do aftermarket pumps include it? I've read that it serves little purpose other than to quiet down the pump a bit, is that true?
Team Owner
Joined: Jul 2004
Posts: 28,353
Likes: 3,253
From: Hartford WI
Good discussion. The ohm test is just for an idea if the coil is good or not. Frankly, I want to replace most of the fuel system but to spread the cost I'll probably do it in pieces with the most likely candidates for failure first (pump).
I believe there are 2 Walbro pumps for our application. One of which requires heavier gauge wire. Would like a more plug and play option. Which is the lesser walbro that uses stock wiring? Will it support 400-450 flywheel hp? I'm hoping for that someday.
Can someone explain the pulsator? Is it in tank? Part of pump? If so, do aftermarket pumps include it? I've read that it serves little purpose other than to quiet down the pump a bit, is that true?
I believe there are 2 Walbro pumps for our application. One of which requires heavier gauge wire. Would like a more plug and play option. Which is the lesser walbro that uses stock wiring? Will it support 400-450 flywheel hp? I'm hoping for that someday.
Can someone explain the pulsator? Is it in tank? Part of pump? If so, do aftermarket pumps include it? I've read that it serves little purpose other than to quiet down the pump a bit, is that true?
I'd get the larger one and the wiring harness if that is what you want.
The pulsator sits between the pump and the fuel line in the gauge assembly. Supposedly it will dampen the fuel pulses with the old style pump. This is a slip on thing and with rubber, well, it can get old. Racetronix sells a kit that has submersible fuel hose and all the bolts you need for the job. That replaces the pulsator.
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,964
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I figured the pump as the most likely part of the fuel system to leave me walking someday.
The Racetronix 255lph C4 kit seems reasonably priced considering it seems to come with everything needed, including the upgrade wire harness which I do like that it is plug and play. Seems like a great option. It doesn't seem to come with the pulsator eliminating parts and I didn't see that advertised on their C4 parts page but I'm sure that's something I can figure out withthem at time of order.
The Racetronix 255lph C4 kit seems reasonably priced considering it seems to come with everything needed, including the upgrade wire harness which I do like that it is plug and play. Seems like a great option. It doesn't seem to come with the pulsator eliminating parts and I didn't see that advertised on their C4 parts page but I'm sure that's something I can figure out withthem at time of order.
Team Owner
Joined: Jul 2004
Posts: 28,353
Likes: 3,253
From: Hartford WI
I figured the pump as the most likely part of the fuel system to leave me walking someday.
The Racetronix 255lph C4 kit seems reasonably priced considering it seems to come with everything needed, including the upgrade wire harness which I do like that it is plug and play. Seems like a great option. It doesn't seem to come with the pulsator eliminating parts and I didn't see that advertised on their C4 parts page but I'm sure that's something I can figure out withthem at time of order.
The Racetronix 255lph C4 kit seems reasonably priced considering it seems to come with everything needed, including the upgrade wire harness which I do like that it is plug and play. Seems like a great option. It doesn't seem to come with the pulsator eliminating parts and I didn't see that advertised on their C4 parts page but I'm sure that's something I can figure out withthem at time of order.