dabcosr

1985 Iroc 305 TPI After a long ride motor would stop an start on the fly. Once it shut down at a stop sign but did restart about a minute later. I made it home had a whistle like a siren sound from fuel tank. Tank is better than 3/4 full. So I know it's not a low tank problem( just filled it up about 70 miles ago not a gauge issue) . Before I drop the tank to do a new fuel pump. Am I headed down the right tracks or should look down a different set of tracks?

8Mike9

The whistle sound may be the check valve doo hickey that is mounted outside of the tank, on a bracket attached to the bottom of the floorpan.

I'd be checking ignition out, like over heating ICM or coil..going to take another hand to check for spark, unless you have a remote stae handy.

dabcosr

The icm is the only thing with the ignition I did not replace.
Reading more about the icm sounds like that could be it. Somtimes long cranking to start, transmission Somtimes does not shift right. I read it gives a signal to the ecm to control other things. Thanks for the input if you or anybody has any other ideas or suggestions please post them.

dabcosr

the Whistle sound is not always there just after I have been running awhile. Shut the car down for a couple mins then restart sound is gone. Do you think this is anything to worry about?

red rock

iTrader: (2)

Do you have a lot of back pressure in the tank when you take the cap off? If so, the vent from the tank may be getting plugged or the purge valve up by the canister under the hood might be stuck. Here is a post on how to clean the tank vent. https://www.thirdgen.org/forums/hist...ent-valve.html Have yo checked the fuel pressure?

dabcosr

Theres no back pressure when I remove gas cap but I do get the occasional gas smell. My 86 iroc got demoed person broad sided me. This 85 was a find but it was garages for 10 years or better. I have been working through the typical car sitting problems. That link is good somthing that I will follow up on thanks

thirdgenttop

ok so I have an 86 Camaro t top with a 2.8 l v6 and I know the fuel pump works iv tested it and I have already replaced the relay can anyone tell me what is going on id love to get my car running asap thanks

dabcosr

I would check for spark if you have another plug laying around you could just pull one of the wires
Put it on the spare plug an ground the outside . Turn the motor over an see if you got spark.
Be careful this is high voltage an it does bite.

dabcosr

Ok I went ahead with the cheap fix first I changed the icm. I don t know how old the old one was the only markings on it was GM. I took it for a spin around the block it does seem more responsive an the tranny does seem to shift better. But the real test will have to wait till Sunday then I will take a long run thanks 8Mike9.

Also Red Rock thanks for the link I will be following thru with that the ringing is very annoying .

8Mike9

We're all here to help...you did use the heat sink compound under the new ICM?

dabcosr

Yes I did also made sure both surfaces were very clean. I'm still
Going to get a fuel pressure gauge or do the borrow one from auto zone. Hopefully Sunday
I will get a long run with it an see what happens.

red rock

iTrader: (2)

Stock pressure is 42-43 lbs with the vacuum disconnected on the regulator and car running, then shut the car off and see if it holds pressure.

bop11

Sounds like you are pulling a vacuum int the tank. I remember a 73 Chevy that actually sucked the walls of the tank together. The car ran out of gas but would only take 3 gallons at the pump. Not saying yu have a flat tank, but the pump will be hard pressed to generate the need 40 psi if the tank is not vented. Whistle is probably air trying to get back in.

dabcosr

I'm going to check the tank vent hopefully this weekend. Going to spend Saturday
At Dover for the race. If not to hung over plan on working on the car Sunday.

Also thank red rock for the pressure numbers. It seems like most people are building there
Camaros up I'm trying to keep mine as close to stock as I can.

thirdgenttop

ok so if I jump the wires my fuel pump kicks on so my relay is not getting the signal to allow power to the pump what should I do

thirdgenttop

ok so I have an 86 Camaro t top with a 2.8 l v6 and I know the fuel pump works iv tested it and I have already replaced the relay can anyone tell me what is going on id love to get my car running asap thanks. if I jump the wires my fuel pump kicks on so my relay is not getting the signal to allow power to the pump what should I do?

8Mike9

Start a new thread

dabcosr

Ok stupid question what is the min fuel pressure for the 305 tpi to run?
Also Red Rock how long should the fuel rails hold pressure? I had 40 to 45 with the vacuume unhooked. And 35 to 40 running. I also have been getting a buzzing noise from the tank. It sound like an internal noise not the vent. It shut down briefly on my ride today and also sitting in the drive way 2 times then I got the fuel pressure gauge and hooked it up and lord an behold it would not shut down!

How do you trouble shoot a interminted problem??????!!!!!!!??????

Sorry just getting frustrated

red rock

iTrader: (2)

Minimum pressure should not be less than 40. It should hold pressure for a short minute. A common issue is the wire plugs for the fuel pump relay. The wire shrinks from the plug and can expose bare wire going into the plugs. If yours are that way, make sure they are still connected into the plugs good and then silicone them. A buzzing noise from the tank (not a high pitched whine) and and intermittent shutdown, sounds like a fuel pump going out. Here is a diagnosis chart. http://chevythunder.com/fuel_system_diagnosis.htm

dabcosr

Very good chart but i would end up at ok. After idoling for about 30 min( problem seems
To happen after long runs) pressure did drop to little bit of nothin. But the motor seems to
Run fine. Shut down an pause turn key on pump buzzes for 2 sec but the pressure does not go above 30
The motor starts an runs. I do believe the pump is the issue.
I have a stupid question. Is it possible that as long as there is fuel in the rails
is it possible for the motor to pull it through the injectors when they open
similar to a carb ???

red rock

iTrader: (2)

No, they have solenoids that open them when needed or you would have gas in the cylinders all the time. Usually when a fuel pump is going, you will get "warning" signs such as what your experiencing. I had one go out in my truck a few years ago, and there was no warning. I was driving, and it just died.

dabcosr

Yea had a company van did the same but it was easy to diagnose as long as I
fed starting fluid through the intake it ran.

Well looks like I am dropping the tank. While the cars in the air I will do the filter.
Are there any other things that I should consider replacing while I have the tank out?

red rock

iTrader: (2)

Just check the lines for aging. Dropping the tank isn't to bad of a job. Siphoning out the gas is the first thing to do, then drop the rear end. Pump, filter, and check the vent. And make sure you get a quality pump, you don't want to do it twice.

dabcosr

Hopefully this will be my last post on this thread. After back tracking an double checking there was an issue with the loaner gauge. I bought almost the same less all the adapters an gismoes. When I turn the switch on I would only get about 2# of pressure then I would start motor an it would take about 1-2 min the pressure would slowly get to 38#. I would dump the pressure and the same very slow back to 38# . Fuel filter was so clogged you could not blow thru it. I hope it is not a sign of future tank failure. But any way the fuel pressure issue has been resolved. Now turn the switch on i get close to 30# start motor instant 38# an when i dump pressure while running it does not go below thirty. Thanks for all the input every one here an past threads.