1990 Convertible strange starting problem

[ptt]

The engine acts like it doesn't want to start then seems to act like its missing but does start.  While feathering the accelerator pedal I can get it up to 2K rpm and hold it steady for about a minute or so and it starts running/driving normally and doesnt reoccur until the car is turned off and sits awhile. It started doing this gradually and now its an every start up occurance.  Im not sure what the problem is!

[Ronnie]

You could have one or more injectors leaking gas while the engine is off causing gas to puddle in the intake manifold. That would make the engine hard to start and run poorly until the excess gas is burned off.  The symptoms you describe are the same as in the old days when you got an engine with a carburetor "flooded".

[B Jake Moran]

I think Ronnie is on to something.  Your post does not have a lot of information.  Mileage, previous maintenance - etc do go a long way to pinpointing it. 

 

Ronnie, could it be a MAF Sensor?  I know in some modern cars I have worked on, if that was in line with or near the EGR system, it could get gunked up and require higher airflow to 'sense' air movement, but then it would do it all of the time.

 

Back to Ronnie's observation - the next time it happens, I would not feather it. Give it about 75% throttle and see if you or someone can check for black smoke out the back.  Black smoke is gas related. 

 

Vacuum leak?  (Requiring higher rpm to overcome)

Edited May 6, 2019 by B Jake Moran (see edit history)

[Ronnie]

1 hour ago, B Jake Moran said:

Ronnie, could it be a MAF Sensor?

Could be the MAF sensor. Easy to find out. Unplug the MAF and see if the problem changes or gets better. My experience with the MAF is the first indication of a problem is the engine consistently idles poorly when stopped at a red light with transmission in gear. I've read where others have experienced the engine not running at all due to a bad MAF. I've never had that happen.

[DAVES89]

I'm thinking either MAF sensor or something also simple but over looked. The Idle Air Control. Clean not only that with a toothbrush and carb cleaner but the cavity it fits into.

[ptt]

I hooked my fuel pressure gauge up and turned the key to ON and the FP gauge only read 29psi.  Turned key off and within 15min it was down to 10psi.  BUT then I noticed the knurled nut end of the gauge hose was leaking to the point that it was dripping!  I shut it down and tightened the knurled end about one eighth turn (as much as I dared to avoid stripping things).  I started the engine and gauge was bouncing rapidly between 28psi and 30psi.  Then the same fuel leak started at the knurled end of the hose again.  It didn't seem to be leaking from the hose but appeared to not be seated between the knurled nut and the service valve.  So an accurate fuel pressure reading was impossible.  Strange because its a LISLE brand gauge and it worked fine on my other car.  Anyway it then stayed at 28-30psi at idle....with the leak.  I took the car for a test drive and didn't notice any lack of performance at all.  even with a WOTrun.  It doesn't have a perfectly smooth idle but then it never has.  The leaking injector sounds very feasible considering the idle and performance gets better after driving/high idling..  One thought...could a partially clogged fuel filter (plus the leaky fitting) cause such a low fuel pressure reading???  I still have to maybe spray the MAF with electrical contact spray.  And clean that IAC too. 

 

 

Edited May 7, 2019 by ptt (see edit history)

[DAVES89]

I looked at your signature line and see that you are getting a lot of miles on your Reattas.

 Let me offer this. The two Reattas I drive daily [the Red and the Black 1989's] each have at least 100,000 miles more then your highest mileage Reatta. I have never replaced a fuel injector for leaking. It has been my experience they just don't. What I do see is that the Idle Air Control and MAF sensor needs to be cleaned. And when you do the MAF sensor take off the screen [held in place with a snap ring] and clean the butterfly with carb cleaner and a tooth brush. What you may also want to consider is the no longer discussed  Sea Foam through the plenum. Another idea is the Oxygen Sensor. All cheap fixes.

 Regarding your fuel pressure, without an exact pressure gauge it's hard to say what the health is of your fuel pump. And if you haven't replaced your fuel filter it's a good idea to do it. You have enough miles to warrant a replacement.; 

[ptt]

Great advice!!!  Now to get myself busy doing it all.  Thanks everyone!!!  I hope to post good results.

[Buick City]

I have been having a similar problem with my 1989 ! It starts right away,but if u don't start out right away it will act like the choke is on , and run rough & stall while ideling.As soon as it is wound out it is fine! I have tried all of the methods mentioned, including new injectors,(it has 330,000 miles ).the only thing I haven't changed is the EGR  any one think this would help ? If you take off right away it drives fine,but any idle it will act leke choking !

[ptt]

I added a bottle of HEET to the gas tank and the problem ceased to exist.  Maybe some bad gas (H2O???) last fill-up???  Hasn't acted up since the HEET was added.....

[Ronnie]

On 5/26/2019 at 1:37 AM, ptt said:

I added a bottle of HEET to the gas tank and the problem ceased to exist.  Maybe some bad gas (H2O???) last fill-up???  Hasn't acted up since the HEET was added.....

 

Thanks for letting us know what resolved your problem.

[2seater]

On 5/26/2019 at 12:37 AM, ptt said:

I added a bottle of HEET to the gas tank and the problem ceased to exist.  Maybe some bad gas (H2O???) last fill-up???  Hasn't acted up since the HEET was added.....

I truly hope it stays fixed but I have always wondered how adding additional alcohol, generally methyl or isopropyl in gas dryers, helps absorb moisture in fuel that already contains up to 10% alcohol (ethyl)?  One bottle of Heet is roughly 10% volume of a gallon so it is little more than 1/2% in a full tank. Kind of a head scratcher. Running a non-ethanol fuel would certainly change the situation.

Edited May 30, 2019 by 2seater (see edit history)

[Ronnie]

It does seem odd the HEET would fix a problem in a fuel injected system where the fuel is constantly being circulated from the tank. to the fuel rail, and back to the tank. That should sufficiently keep any water mixed with the fuel so the engine would run satisfactorily - although it might miss or sputter when a bit of water got to an injector it should still start.    With that said I did have a Chevy Cavalier that had over a gallon of water pumped into the tank from a dirty service station tank  that prevented the engine from running at all. In that case the tank and and filters had to be removed to get out all the water before the engine would run again.  I don't think adding HEET would have helped a situation like that.

 

In the old days water was a bigger problem, especially in cold weather,  because any water in the tank would separate and go to the bottom where it was the first thing picked up and sent to the carburetor bowl. There was no circulation of the fuel in that type of fuel system.  Adding alcohol would absorb the water so it would mix with the gasoline where it could be burned in the engine.  My father would add half a bottle of rubbing alcohol each time he filled the tank in the winter.

[ptt]

Its been a few fill-ups since I added the HEET to the tank and the sputtering cold startup went away.  Alas...its back with a vengeance.  The idle will smooth out, as before, after a minute or so.  Could a MAF going bad possibly be the culprit???  I seem to recall my '90 Coupe doing this and replacing the MAF cured the cold start sputtering.  In fact it has consistantly started very quickly every since the new MAF was installed.  Another thought came to mind is that the station I frequent (Quik Trip) is moving and I will be using a different place to get fuel so maybe Ive been getting fuel at the bottom of the underground tank recently....😱

[padgett]

Can't check at moment but think the diagnostics can display MAF.

Edited June 15, 2019 by padgett (see edit history)

[ChrisWhewell]

If adding heet provided immediate positive results, that tells you something.   Symptoms described are of water in the gas.    Given the ethanol in the fuel these days, gasoline is permitted to have about 0.4% water in it, a great way for petrochem companies to make extra profit, by selling water, imagine 0.4% of the daily dollar amount of gasoline sold in the usa, being water, a major boon for oil companies.  When it is at max water spec such as from condensation during transport or storage at the gas station, any further water such as from  temperature changes and attendant condensation in your tank will cause beads of h2o to form at the lowest point in the tank, the water being denser than the remainder of the fuel.       I had the same issue with my Deere tractor last week, stopped it on a hill and went to start it and... no dice.    had to move it to level ground and it fired right up.    heet comes in two versions , one is methanol, the other is isopropanol.   The latter is better in fuel injected vehicles.