Time for New Injectors?

[Wade Nelson]

I decided to invest in a new set of injectors after speaking with a local mechanic friend.

Vehicle is 1980 280ZX, 230k miles, which runs terrific, and gets excellent MPGs.

My ZX usually starts IMMEDIATELY, and other times cranks and cranks, AS IF the fuel rail has lost pressure. In addition I've twice found liquid fuel in BCCD vaccum lines and a strong aroma of fuel on startup / underhood SUGGESTING a sometimes-leaking injector backfilling the throttle body.

I've recently tried driving around with the Cold Start Valve unplugged, and it didn't seem to change things one way or the other. I figured it would either lengthen my starting cranks, or perhaps solve the loss of pressure problem. It did neither.

So that LACK of change suggests it may be one of the primary injectors that's leaking.

Ed, a local mechanic I've worked with for years, told me he has cut apart a few failed or failing injectors over the years and what he most often found was that a return spring where a couple of the coils had broken off. That seems consistent with an injector that OCCASIONALLY fails to close, and leaks fuel.

It also suggests that rebuilding an injector may not solve the problem. Do the springs get replaced?

I was going to pop for some NOS Bosch injectors some guy in California had, he was asking "only" $200, but another Z owner here....NEVERMIND!!!

So I went with some STANDARD injectors being offered on Ebay. I don't know if they'll come with new seals or if I'll have to chase those down.

At 200+K miles, it just seemed like TIME, given my symptoms.

So what has replacing injectors done for you? Boosted performance or MPG's? Improved starting at all?

[Zed Head]

The most noticeable effect for me was a smoother idle, and smoother high RPM running. Due to a better power balance between cylinders, I assume. I had one of those sometimes leaking injectors also, and later I built a tester and found about a 20% difference in output from high to low in the old injectors. They were pretty bad.

Also, now that all ports on the fuel system are sealed, the engine starts right up, even after days of sitting. No leak-down.

Did you plug the fuel line to the CSV or just disconnect the electrical?

[Wade Nelson]

I just pulled the electrical. I figured with no electrical input it would stay in whatever position it was in last, whether closed, or leaking and it would be pretty easy to figure out which. It appears to be closed. I'm replacing it anyway.

Do you still have your tester?

[Montezuma]

I decided to invest in a new set of injectors after speaking with a local mechanic friend.

Vehicle is 1980 280ZX, 230k miles, which runs terrific, and gets excellent MPGs.

My ZX usually starts IMMEDIATELY, and other times cranks and cranks, AS IF the fuel rail has lost pressure. In addition I've twice found liquid fuel in BCCD vaccum lines and a strong aroma of fuel on startup / underhood SUGGESTING a sometimes-leaking injector backfilling the throttle body.

I've recently tried driving around with the Cold Start Valve unplugged, and it didn't seem to change things one way or the other. I figured it would either lengthen my starting cranks, or perhaps solve the loss of pressure problem. It did neither.

So that LACK of change suggests it may be one of the primary injectors that's leaking.

Ed, a local mechanic I've worked with for years, told me he has cut apart a few failed or failing injectors over the years and what he most often found was that a return spring where a couple of the coils had broken off. That seems consistent with an injector that OCCASIONALLY fails to close, and leaks fuel.

It also suggests that rebuilding an injector may not solve the problem. Do the springs get replaced?

I was going to pop for some NOS Bosch injectors some guy in California had, he was asking "only" $200, but another Z owner here....NEVERMIND!!!

So I went with some STANDARD injectors being offered on Ebay. I don't know if they'll come with new seals or if I'll have to chase those down.

At 200+K miles, it just seemed like TIME, given my symptoms.

So what has replacing injectors done for you? Boosted performance or MPG's? Improved starting at all?

You called about them???? I had the message but screwed up by deleting the message instead of saving it or I would have sold them to you. I did not know it was you who called. I am so sorry.

[siteunseen]

They made all the difference in the world on my car. 3 of the old ones were cracked out and falling apart. I bought new Standard FJ707 with the long hose and they came with the big O ring as well as the smaller one and the clamp. Got them at rockauto.com for about $165.

[Zed Head]

Do you still have your tester?

I do but I can't recommend that anyone build one. It's a dangerous device unless you use a gas substitute. I used gasoline and was super careful, but even so I don't think I'll ever use it with gas again. It made me too nervous, especially with the Bosch injectors, which really vaporized the fuel, compared to a stream from some other injectors. I'd have to locate a less flammable substitute liquid.