F9 13B Turbo Buggy - runs with no fuel pressure?


F9 13B Turbo Buggy - runs with no fuel pressure?

Postby azrotor » Wed Sep 05, 2007 5:36 am

Newbie to Haltech here. Oldster to rotaries.
A sand rail with an early 13B, T44, F9, dual MSD 6A's, Nitrous. It was brought in thinking he ate a motor, he thought he swallowed some sand.
Cranked like it was dead.
Cranks slow but found that is due to incorrect starter for the rotary.
Motor was full of fuel. Compression started out erratic, then got better. Still low but buy all standards it should start and run 5.9 front 5.6 rear 130rpm.

Fire was erratic, eventually found 3 plug connectors broken or ready to break. 1 coil 12v wire connector intermittently connecting. Felt like I was doing the Plymouth Trouble Shooting contest.

Found other issues with ignition and wiring fixed them.

It would now fire and die, acting like it is in closed loop. (no O2 or idle control)

Tried just letting the fuel pump prime then turned it off. Motor fired, cleared out and tried to run. Then pulled the two inboard injectors. That was when it would run fine without fuel pump on. (fuel pressure gauge shows 0 ) Hook either injector up and it dies.

Fuel pressure with pump on read 68psi, knocked it down to 24psi. Now it runs pretty darn good on two injectors. Still dies when either of the other injectors is powered.

According to the readings for the sensors they are suppose to be good.

I do get a bunch of engine and I/O flags.
I/O now 70
engine 9

engine fuel settings,
4 cyl
throttle position at idle - 13
any other particulars needed please let me know.

According to the owner this thing was running fine. It blew off an intake hose which he put back on. Said it seemed to run alright. He has been doing some electical work on it. Installing a tach and laying in wires for the intercooler fan. (which circuit was blowing fuses due to a bad connection in that harness. Repaired that problem)
I fear I may not be getting the whole story.

Thanks upfront for any input,


<i>Edited by: azrotor at: 9/5/07 8:18 am


Re: F9 13B Turbo Buggy - runs with no fuel pressure?

Postby THR RX7 » Wed Sep 05, 2007 10:32 am

Ok, lets start with the obvious, what is the fuel pressure set at, is the fuel pump operational (does it work)? if there's on thing ive come to learn from working on Haltechs, if it was running fine at one point and nothing in the haltech changed, there no reason for it to not run, so the problem must lie somewhere else, when you said 5.6 and 5.9 at 130rpm what did you mean? psi of pressure? if that engine has no compression why dont you just take it appart or pull the intake or exhaust manifolds to look inside?

Claudio RX-7
[email protected]
Dominican Republic
Tel. +1(809)763.0202
Tel. +1(678)810.0763
<i>Edited by: THR RX7  at: 9/5/07 10:32 am


more info, latest update

Postby azrotor » Thu Sep 06, 2007 4:36 am

Sorry must not have been clear.

Those are the averaged compression #'s in kg/cm. roughly 70/80 lb/in.

Looked inside and everythings good.

I don't suspect the haltech myself, the only thing I don't like is it is hard mounted to the buggy floor and not protected better. Connector area really had a lot of sand in it. I am leaning to what it is being fed.

There have been a lot of electrical issues. But not from quality of original worksmanship. I think just age and normal wear and tear on this platform.

To answer your question, came in with fuel pressure 68psi. Would not run at all, flooded out straight away.
I found it would run for a minute or so (pucking black smoke) when I disconnected the two inboard injectors. I then turned the fuel pressure down to 24psi, where it now runs decently. (isn't 68 what haltech recommends?)

Another thing I just found, the manifold pressure is all over the place, bouncing anywhere from 4psi to 7in. at idle.

V/P gauge show good 13in of vac.

The map sensor is just hanging in midair, below some of the fuel system. Yes, full of fuel and oil. Looks like it has been replaced before the part # doesn't match anything from the haltech manual.
041006 2134 prt #12569240 is what is on this MAP sensor. It hasn't responded to cleaning.

Will let you know what happens when I try a different MAP sensor.

btw I am now getting 7 I/O flags and 0 engine, is there anyway to find out what these are? These numbers have been getting lower the more I repair.


Re: more info, latest update

Postby azrotor » Thu Sep 06, 2007 9:00 am

Bingo. MAP sensor bad. Where do I get one? BAR3

Plugged in a mazda sensor, fired - died. Hooked up all 4 injectors. Runs. Next, I will bump the fuel pressure back up.

manifold vacuum steady 15.5 on haltech. Gauge varies 14/16.

Just fine tuning now I recon.


Re: more info, latest update

Postby THR RX7 » Sun Sep 09, 2007 2:28 pm

Any Haltech dealer can supply a 3bar map sensor, they normally run around 90-110 bucks with connector.

Good to hear you solved the problem. I've been told by a guy that works on haltechs and sand rails with V8s that normally the wiring on those things has to be super high quality cause of the vibrations and abuse they go through, otherwise you get problems.
Claudio RX-7
[email protected]
Dominican Republic
Tel. +1(809)763.0202
Tel. +1(678)810.0763


Re: more info, latest update

Postby azrotor » Wed Sep 12, 2007 1:45 am

Thanks Claudio,

Yep, know about the wiring. This buggy is professionally build, originally they didn't cut corners. Just age. If I ran one of these I would be checking the wire connectors after every season.

Talked with another rotary shop that does a lot of rotary sand rails and was told they have had problems and known others that have had problems with the haltech sensors. I see on other forums that the GM map3 is recommended. It is a GM map1 that was in it when it was brought in. I imagine that the haltech didn't know what was happening even when it worked.

What happens when you use a map1 and the ecu is set for map3?

I used a stock mazda rx7 sensor that seems to work. Don't know if I can trust it for over 15psi though.

Also I called a couple of dealers and they don't stock any map2 or 3's. (they don't do any turbo sales)

Mary at RX7.com is checking now to see if they have one laying around.

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