Hi All,

Have a weird issue with an 87 GL Sedan I bought recently.  The car has 26k miles original and is mint. With that mileage, it has sat around alot.  I did a tune up - plugs, wires, dist cap, set timing etc.  It actually runs really well aside from one strange issue.

It starts and runs fine.  As it warms up and the idle drops, it will idle around 900 and buck a little (almost like amiss).

Then, if I shut off the car, and start it again, the idle settles perfectly smooth at 800 (since its automatic), no buck or miss.

At this point, if I go for a drive, it runs perfect.  However, If I floor the gas pedal (or close to it), it will then always idle between 900-1200 (depending on how far I had pressed the gas) and will buck/miss a little. If I shut the car off, and restart, it goes back to running/idling perfect immediately, until I floor it again.

Given this, I suspect it is something to do with the secondary's, or something related to them, perhaps something not closing after it opens, until I shut the car off and it loses all vacuum.

Any Hitachi experts care to weigh in?

 

Thanks

John

 

Edited October 7, 20214 yr by Scoby4wd

Sounds like fuel system problem.  Given that the car is that old and sitting around a lot you'll likely have to flush out the whole fuel system, with new filters. and then go from there.  Maybe add some cheap additives and keep your fingers crossed.

I feel like its mechanical in nature, since it will run perfect until it gets floored.  Such a strange one.

 

I will check the fuel system though, I do have a filter for it.

So that’s the end of the carb run. Mid 1987 production. 
 

How’s the accelerator pump look ? Front of carb with rubber boot. The new fuel eats those up depending on what you gas up with. Just a thought. May not be related but generally check the carb over because the newer fuels are like mice on cheese to your rubber boot and gaskets and seals. Ok that’s an exaggeration but you know what I mean. Read about it on vintage machine sites.
 

Also check your distributor for play. 

And age has a way of doing in the intake manifold gaskets. But you’d see a mist out the exhaust if that were the case. 
 

Seems like you found a “pull along”. Was it an RV tug-around ? Or an older lady car ? We also once had a 26k car. Old lady car.

Have fun , enjoy ! 

Non Ethanol fuel is available, usually near Marinas or boat areas.   I have been putting Non Ethanol fuel in my thirty year old Buick, and it runs noticeably better.   Gas Buddy or a similar site, might be a way to search for such fuel.   

On 10/11/2021 at 5:50 AM, newmexguy said:

Non Ethanol fuel is available, usually near Marinas or boat areas.   I have been putting Non Ethanol fuel in my thirty year old Buick, and it runs noticeably better.   Gas Buddy or a similar site, might be a way to search for such fuel.   

I've ran the "clear gas" in my 50 year old Chevrolet, and I saw very little difference from E10 other than the fact that it doesn't evaporate so damn fast when it sits for more than 3 days. I'm not sure the extra .50 is worth it. However, some people like yourself have seen real results from it.

For anyone that wants to try it, here's THE site for finding ethanol free gas:

https://www.pure-gas.org/index.jsp?stateprov=or

I assume this is a Hitachi  carb, and you can get the secondary hung up when you floor it. I've had this happen on a non-Subaru, but it's probably the same carb. Next time it happens to you, get out and check the vacuum secondary plate linkage on the outside of the carb.

Edited October 12, 20214 yr by subaru1988