Question: Under pressure

[English Guy]

Please could someone tell me the pressure rating for stock/standard replacement fuel injectors for 1989 L98 engine?Merry Christmas all.

 

[dwsjr50]

I believe 40 to 47lbs. of fuel pressure required before start up. The pressure should drop about 3-10 lbs when idling . My experience using stock pressure regulator. Somebody with an FSM can fill you in with fine tuning.

Donald

 

[gmjunkie]

22#

 

[gmjunkie]

I believe 40 to 47lbs. of fuel pressure required before start up. The pressure should drop about 3-10 lbs when idling . My experience using stock pressure regulator. Somebody with an FSM can fill you in with fine tuning.

Donald

Thats for a LT1/LT4 car!! L98's 34-39#

 

[TedC]

L98s used different fuel PSIs based on model year. Both my stock 1988 and 1989 produced ratings as per dwsjr50's comments above. Here are the readings I like to measure. On (not running, should hear fuel pressure relay engage), running with vacuum line attached to regulator (you will see reduced pressures because the vacuum is used to signal low power demands), running no vacuum line at idle, runnng with vacuum line at WOT (critical for top preformance). Also, watch how long the pressure holds when engine is not running. On my 1988, injectors were leaking down when hot. This hot soak condition caused hard starting when restarting hot. I agree with Junk on the stock injector size used in 1989. You may find conflicting information that they are 24#s, or you can replace with 24#. Stick to stock size unless you plan on reprogramming the PROM.

 

[English Guy]

Hi there TEDC,What is 'hot soak'?I've not heard of that expression before.Seasons greetings,Brian.

 

[English Guy]

Thank you all for your responses folks.

 

[TedC]

Brian, Happy Holidays!!! If you shut off your engine while it is hot (operating temp) and let it sit for 5-10 minutes, this is hot soak. Hot soak occurs because the hood is closed and nothing is running to cool it off (i.e. fan). On my 1988, the injectors were leaking so much that during hot soak they would cause an extra rich condition which made is very difficult to start restart.

 

[English Guy]

Thanks TEDC ,would new injectors be affected by hot soak.All the best,Brian

 

[TedC]

No, because they should not be leaking under normal levels of fuel pressure in the line. Internal leaking is one of the common issues as injectors age. My1988 never ran better after replacing the injectors. Just twist the key and it would start under any condition. On my 1989, the prior owner had the dealership replace the stock Multecs with the same due to internal shorts, not because of internal leaks. He was having starting issues. GM dropped the 9th injector called a cold start injector in 1989. GM also reprogrammed the PROM to add a delayed start during crank to help build up oil pressure before engine start.

 

[tonylong]

English Guy - I've been meaning to ask - s your vette a RHD or LHD?
and if RHD, did you get that done, or was it like that when you got it?