hot start problem

[firstsupra]

I have a 1987 Supra with the 7M GTE engine, that does not like to start when hot. This is random, but usually happens when you shut the car
off, come back 15-20 mins later and it takes a lot of cranking to get it started. I have checked the fuel pressure and it is to spec. -- at idle speed,
press. reg. vacuum hose on or off and there was no leak down for 15 min. after shutdown. The plugs are new, gapped at .036 (what is best?)
new fuel filter and I use gasohol (opinions on fuel?)
I have heard suggestions as simple as 2-3 tanks of gas with injector cleaner to TPS problems to cold start injector problems. Cold start
is not a problem. I did have a TPS connection "code" once (the car wouldn't start at all). I cleaned and worked on the connectiion and it
hasn't happened again.

Help!!!

Another question. What is normal oil pressure for these? Mine is 40 psi at idle, 25-30 at 3000 rpm cruising and 0nly 10-15 at hot idle.
This doesn't look good to me.

thanks!

 

[GrimJack]

The hot start problem could be heat soak. There is a VSV on the underside of the intake manifold, near the front, that controls whether the fuel pressure regulator gets manifold or ambient pressure. In the case of heat soak, it is supposed to switch to ambient pressure, which increases your fuel pressure and flushes the boiled fuel out of the rail. Verify that VSV is still there and working.

 

[jdub]

I have a 1987 Supra with the 7M GTE engine, that does not like to start when hot. This is random, but usually happens when you shut the car
off, come back 15-20 mins later and it takes a lot of cranking to get it started. I have checked the fuel pressure and it is to spec. -- at idle speed,
press. reg. vacuum hose on or off and there was no leak down for 15 min. after shutdown. The plugs are new, gapped at .036 (what is best?)
new fuel filter and I use gasohol (opinions on fuel?)
I have heard suggestions as simple as 2-3 tanks of gas with injector cleaner to TPS problems to cold start injector problems. Cold start
is not a problem. I did have a TPS connection "code" once (the car wouldn't start at all). I cleaned and worked on the connectiion and it
hasn't happened again.

Help!!!

Another question. What is normal oil pressure for these? Mine is 40 psi at idle, 25-30 at 3000 rpm cruising and 0nly 10-15 at hot idle.
This doesn't look good to me.

thanks!

Gasohol can make hot start problems worse. What E?
Your oil pressure is good at the idle side, a lil low (but not bad) for the hot pressure. What oil make/grade?

The hot start problem could be heat soak. There is a VSV on the underside of the intake manifold, near the front, that controls whether the fuel pressure regulator gets manifold or ambient pressure. In the case of heat soak, it is supposed to switch to ambient pressure, which increases your fuel pressure and flushes the boiled fuel out of the rail. Verify that VSV is still there and working.

Just disconnect the vac line to the FPR on the next hot start and see if it makes a difference.

 

[firstsupra]

OK, my dumb, what is a VSV? I understand what you are talking about and can probably find it, I just havn,t heard the term before.

I use 10% ethanol. The oil is Valvoline 20-50 racing. That 40 psi reading is Cold idle. Hot idle is 10-15 PSI.

 

[Jtsan]

VSV= vacuum switching valve. There are a couple of them. But we only need to look at the fp vsv. I would do what grimjack said. I had a similar problem. Crank no start when hot. Checked the fp vsv and it was missing. Replaced it and problem solved.

 

[jdub]

OK, my dumb, what is a VSV? I understand what you are talking about and can probably find it, I just havn,t heard the term before.

I use 10% ethanol. The oil is Valvoline 20-50 racing. That 40 psi reading is Cold idle. Hot idle is 10-15 PSI.

E10 should not be a problem at all. That oil is way too thick....no wonder your hot idle oil psi is so high.

 

[Nick M]

The VSV mentioned in the thread is behind the alternator. That is much faster to take off than the intake manifold.