Summertime Blues, or, coping with vapor lock and OEM Options

[1970 Neun vierzehn]

I've posted this query here 'cause I figured maybe there would be no smart-a** replies that would be forthcoming from the "garage" forum.

Yes, I know about the front trunk placement of the fuel pump, but for a 70/4, that's hardly original. The only "trick" I am aware of is keeping the fuel tank mostly full, thereby lessening the effect of overly warm gasoline returning to the fuel pump.

Last Sunday, after a particularly spirited drive of some length, and exiting the interstate with about a 1/4 tank of fuel, the dreaded no-idle, sluggish throttle response at low rpm, and frequent stalling made the last few miles challenging. Thankfully, traffic kept moving, as I'm sure that had I been caught in lots of stop-n-go, the 914 would have died until things cooled down.

So, in the interest of keeping things original, does anyone have any other suggestions, if not to completely eliminate, but at least reduce the likelihood of vapor-lock problems?

Paul

[Tom_T]

Hey Paul, the factory - via VoA & Porsche+Audi - had a service bulletin in the late 70's on this FP relo for pre-75 914s. While I've not seen the actual paperwork, my long time factory trained mechanic Hans had done it on mine in 78 or 79 IIRC, after I got stuck for 3+ hrs. in beautiful downtown Blythe in 120+ weather that summer.

For this factory recco, the FP gets moved up under the steering rack cover behind the ZF rack just next to the access hole in the floor pan up there where the fuel lines go to the tunnel, & only requires some mounting screws into the pan - rather than the wholesale cutting which the non-factory recco trunk relo does. The fuel lines spice in at that tunnel access hole where the fuel lines daylight there to attach to the lower fuel tank fittings; & the electrical wiring is run under the passenger rocker panel.

I think that AA's kit is set up to do essentially the same set-up. Do remember to install the FP bracket with the rubber isolators, so you don't transmit the vibes so much to the floorpan.

Advantages to this location are:

1 - the fuel lines are already in the tunnel & up to the tank at the floorpan/tunnel portal,

2 - power can be run up from the stock FP location along the L rocker/sill space using the threshold sill's triangle-braces' holes,

3 - access is easy for repairs by removing the steering gear cover pan (as opposed to inside under the fuel tank that then needs removal for any work),

4 - which also serves to protect the FP & fittings from road debris/mud/water/snow/salt/etc., requires no cutting of the trunk or other body panels (as in the F trunk option),

5 - it's in a naturally cooled area due to the underbody airflow & away from the engine bay's heat to eliminate the vapor lock problem,

6 - it's essentially the same location as for the fuel filter change on the 70-74 914's, so it also promotes regular inspection whenever the filter is changed - since it's right in your or the mechanic's face.

7 - & since it's based on a factory service bulletin to deal with this problem, then it should past CW muster, in the same way as the HO Recall fix for the battery cover & engine bay fuel lines, or changing out the improper p/n ...-00 Fuchs Alloy Wheels without the back groove to seat the hubcentric front hubs properly with the proper p/n ....-01 wheels under the BO Recall.

Here are some pix from mine as I'm opening it up for the resto, but it's not pretty after sitting on blocks in my garage for the past 25 years - so "please excuse out dust, rust & grime!"


- FP wiring behind pass. rocker cover panel


- Looking at FP from behind F pass tire side


- FP connections at floor pan/tunnel access portal


- Looking at FP from behind F driver tire side

Perhaps the incomparable Mr. Bowlsby has the old VoA/P+A Service Bulletin on the fuel pump relocation in his files?? (IMG:style_emoticons/default/confused24.gif)

BTW - I understand about some of the responses in the Garage,but I think most of the folks over there mean well (smart-a's aside)!
... I can add some smart-A comments of my own here if you'd like!!?? (IMG:style_emoticons/default/biggrin.gif)

Hope this helps! (IMG:style_emoticons/default/popcorn[1].gif)

[Ericv1]

Hey Paul, the factory - via VoA & Porsche+Audi - had a service bulletin in the late 70's on this FP relo for pre-75 914s. While I've not seen the actual paperwork, my long time factory trained mechanic Hans had done it on mine in 78 or 79 IIRC, after I got stuck for 3+ hrs. in beautiful downtown Blythe in 120+ weather that summer.

For this factory recco, the FP gets moved up under the steering rack cover behind the ZF rack just next to the access hole in the floor pan up there where the fuel lines go to the tunnel, & only requires some mounting screws into the pan - rather than the wholesale cutting which the non-factory recco trunk relo does. The fuel lines spice in at that tunnel access hole where the fuel lines daylight there to attach to the lower fuel tank fittings; & the electrical wiring is run under the passenger rocker panel.

I think that AA's kit is set up to do essentially the same set-up. Do remember to install the FP bracket with the rubber isolators, so you don't transmit the vibes so much to the floorpan.

Advantages to this location are:

1 - the fuel lines are already in the tunnel & up to the tank at the floorpan/tunnel portal,

2 - power can be run up from the stock FP location along the L rocker/sill space using the threshold sill's triangle-braces' holes,

3 - access is easy for repairs by removing the steering gear cover pan (as opposed to inside under the fuel tank that then needs removal for any work),

4 - which also serves to protect the FP & fittings from road debris/mud/water/snow/salt/etc., requires no cutting of the trunk or other body panels (as in the F trunk option),

5 - it's in a naturally cooled area due to the underbody airflow & away from the engine bay's heat to eliminate the vapor lock problem,

6 - it's essentially the same location as for the fuel filter change on the 70-74 914's, so it also promotes regular inspection whenever the filter is changed - since it's right in your or the mechanic's face.

7 - & since it's based on a factory service bulletin to deal with this problem, then it should past CW muster, in the same way as the HO Recall fix for the battery cover & engine bay fuel lines, or changing out the improper p/n ...-00 Fuchs Alloy Wheels without the back groove to seat the hubcentric front hubs properly with the proper p/n ....-01 wheels under the BO Recall.

Here are some pix from mine as I'm opening it up for the resto, but it's not pretty after sitting on blocks in my garage for the past 25 years - so "please excuse out dust, rust & grime!"


- FP wiring behind pass. rocker cover panel


- Looking at FP from behind F pass tire side


- FP connections at floor pan/tunnel access portal


- Looking at FP from behind F driver tire side

Perhaps the incomparable Mr. Bowlsby has the old VoA/P+A Service Bulletin on the fuel pump relocation in his files?? (IMG:style_emoticons/default/confused24.gif)

BTW - I understand about some of the responses in the Garage,but I think most of the folks over there mean well (smart-a's aside)!
... I can add some smart-A comments of my own here if you'd like!!?? (IMG:style_emoticons/default/biggrin.gif)

Hope this helps! (IMG:style_emoticons/default/popcorn[1].gif)

I agree. I had mine relocated on my 74 for roughly two years and there's been no issues with driveability. The access underneath the car is a little tight to change a filter, but it can be done. The last time I just pulled the tank because it was easier and less time consuming. It took more time to put the car on jacks and remove the access cover than it did just to pull the tank. I also remember 75 and 76 MY's having an access board in the front trunk compartment that made servicing the filter easier.

[tod914]

My 73 pump was mounted on the firewall by one of the PO's. Was ready to fall off. I put it back in the stock location. I get an intermitant issue when it's hot. After I drive the car for a while, shut it off then let it sit, when I restart it the idle wants to die. Issue lasts a couple minutes till the car warms up again. On Brad's site, he mentions that's a problem due to the heads cooling down at a different rate than the engine. Thinking it might be more vapor lock related though. Would using that silver insulation help reflect heat from the pump? Any type of air deflector available? Curious to see how you resolve your issue Paul.

[IronHillRestorations]

I can't remember all the features of the fuel pump recall, but I'm fairly certain one was to mount the fuel pump low on the firewall. You might contact Brad Mayeur as he was a dealer mechanic back then and did some of the recall mods. As a factory recall this would be acceptable in any concours.

[Ericv1]

I can't remember all the features of the fuel pump recall, but I'm fairly certain one was to mount the fuel pump low on the firewall. You might contact Brad Mayeur as he was a dealer mechanic back then and did some of the recall mods. As a factory recall this would be acceptable in any concours.

My 70 had the fuel pump relocated to the low portion of the firewall. I never had any issues with vapor lock.

[Pat Garvey]

I've posted this query here 'cause I figured maybe there would be no smart-a** replies that would be forthcoming from the "garage" forum.

Yes, I know about the front trunk placement of the fuel pump, but for a 70/4, that's hardly original. The only "trick" I am aware of is keeping the fuel tank mostly full, thereby lessening the effect of overly warm gasoline returning to the fuel pump.

Last Sunday, after a particularly spirited drive of some length, and exiting the interstate with about a 1/4 tank of fuel, the dreaded no-idle, sluggish throttle response at low rpm, and frequent stalling made the last few miles challenging. Thankfully, traffic kept moving, as I'm sure that had I been caught in lots of stop-n-go, the 914 would have died until things cooled down.

So, in the interest of keeping things original, does anyone have any other suggestions, if not to completely eliminate, but at least reduce the likelihood of vapor-lock problems?

Paul

Paul, in the interest of keeping things original, do so. Live with the occasional vapor lock.
I know that your 914 is dead nuts/right on when it comes to originality. To cut the bulkhead for placement of the fuel pump would be sacriligous (sp).
Tom's note applies to late versions, not early (pre-74), though it can be made to work. But, it wouldn't be original.

Look, the heat in your area has been sidnificant, as it is here. When it's this hot, you're prone to vapor lock. Nothing new here - we've had this problem on & off for 40 years.

Live with it, my friend. It's rare. Keep it original.

Pat

ps - I've never had the problem with my 72. Course it hasn't run in 4 years!

[monkeyboy]

Could you make a temporary heat shield that attached to some existing bolts? Maybe some sort of scoop? I know it's in a bad spot, but there has to be something that can be done.